diff --git a/Documentation/SubmittingPatches b/Documentation/SubmittingPatches
new file mode 100644
index 0000000000..6121e902ae
--- /dev/null
+++ b/Documentation/SubmittingPatches
@@ -0,0 +1,130 @@
+I started reading over the SubmittingPatches document for Linux
+kernel, primarily because I wanted to have a document similar to
+it for the core GIT to make sure people understand what they are
+doing when they write "Signed-off-by" line.
+
+But the patch submission requirements are a lot more relaxed
+here, because the core GIT is thousand times smaller ;-).  So
+here is only the relevant bits.
+
+
+(1) Make separate commits for logically separate changes.
+
+Unless your patch is really trivial, you should not be sending
+out a patch that was generated between your working tree and
+your commit head.  Instead, always make a commit with complete
+commit message and generate a series of patches from your
+repository.  It is a good discipline.
+
+Describe the technical detail of the change(s).
+
+If your description starts to get long, that's a sign that you
+probably need to split up your commit to finer grained pieces.
+
+
+(2) Generate your patch using git/cogito out of your commits.
+
+git diff tools generate unidiff which is the preferred format.
+You do not have to be afraid to use -M option to "git diff" or
+"git format-patch", if your patch involves file renames.  The
+receiving end can handle them just fine.
+
+Please make sure your patch does not include any extra files
+which do not belong in a patch submission.  Make sure to review
+your patch after generating it, to ensure accuracy.  Before
+sending out, please make sure it cleanly applies to the "master"
+branch head.
+
+
+(3) Sending your patches.
+
+People on the git mailing list needs to be able to read and
+comment on the changes you are submitting.  It is important for
+a developer to be able to "quote" your changes, using standard
+e-mail tools, so that they may comment on specific portions of
+your code.  For this reason, all patches should be submitting
+e-mail "inline".  WARNING: Be wary of your MUAs word-wrap
+corrupting your patch.  Do not cut-n-paste your patch.
+
+It is common convention to prefix your subject line with
+[PATCH].  This lets people easily distinguish patches from other
+e-mail discussions.
+
+"git format-patch" command follows the best current practice to
+format the body of an e-mail message.  At the beginning of the
+patch should come your commit message, ending with the
+Signed-off-by: lines, and a line that consists of three dashes,
+followed by the diffstat information and the patch itself.  If
+you are forwarding a patch from somebody else, optionally, at
+the beginning of the e-mail message just before the commit
+message starts, you can put a "From: " line to name that person.
+
+You often want to add additional explanation about the patch,
+other than the commit message itself.  Place such "cover letter"
+material between the three dash lines and the diffstat.
+
+Do not attach the patch as a MIME attachment, compressed or not.
+Do not let your e-mail client send quoted-printable.  Many
+popular e-mail applications will not always transmit a MIME
+attachment as plain text, making it impossible to comment on
+your code.  A MIME attachment also takes a bit more time to
+process.  This does not decrease the likelihood of your
+MIME-attached change being accepted, but it makes it more likely
+that it will be postponed.
+
+Exception:  If your mailer is mangling patches then someone may ask
+you to re-send them using MIME.
+
+Note that your maintainer does not subscribe to the git mailing
+list (he reads it via mail-to-news gateway).  If your patch is
+for discussion first, send it "To:" the mailing list, and
+optoinally "cc:" him.  If it is trivially correct or after list
+discussion reached consensus, send it "To:" the maintainer and
+optionally "cc:" the list.
+
+
+(6) Sign your work
+
+To improve tracking of who did what, we've borrowed the
+"sign-off" procedure from the Linux kernel project on patches
+that are being emailed around.  Although core GIT is a lot
+smaller project it is a good discipline to follow it.
+
+The sign-off is a simple line at the end of the explanation for
+the patch, which certifies that you wrote it or otherwise have
+the right to pass it on as a open-source patch.  The rules are
+pretty simple: if you can certify the below:
+
+        Developer's Certificate of Origin 1.1
+
+        By making a contribution to this project, I certify that:
+
+        (a) The contribution was created in whole or in part by me and I
+            have the right to submit it under the open source license
+            indicated in the file; or
+
+        (b) The contribution is based upon previous work that, to the best
+            of my knowledge, is covered under an appropriate open source
+            license and I have the right under that license to submit that
+            work with modifications, whether created in whole or in part
+            by me, under the same open source license (unless I am
+            permitted to submit under a different license), as indicated
+            in the file; or
+
+        (c) The contribution was provided directly to me by some other
+            person who certified (a), (b) or (c) and I have not modified
+            it.
+
+	(d) I understand and agree that this project and the contribution
+	    are public and that a record of the contribution (including all
+	    personal information I submit with it, including my sign-off) is
+	    maintained indefinitely and may be redistributed consistent with
+	    this project or the open source license(s) involved.
+
+then you just add a line saying
+
+	Signed-off-by: Random J Developer <random@developer.example.org>
+
+Some people also put extra tags at the end.  They'll just be ignored for
+now, but you can do this to mark internal company procedures or just
+point out some special detail about the sign-off.
diff --git a/checkout-cache.c b/checkout-cache.c
index 8d67403ae8..31ff577500 100644
--- a/checkout-cache.c
+++ b/checkout-cache.c
@@ -78,10 +78,11 @@ static int checkout_all(void)
 static const char checkout_cache_usage[] =
 "git-checkout-cache [-u] [-q] [-a] [-f] [-n] [--prefix=<string>] [--] <file>...";
 
+static struct cache_file cache_file;
+
 int main(int argc, char **argv)
 {
 	int i, force_filename = 0;
-	struct cache_file cache_file;
 	int newfd = -1;
 
 	if (read_cache() < 0) {
diff --git a/diff.c b/diff.c
index 3e52fec187..bb2a43b5b0 100644
--- a/diff.c
+++ b/diff.c
@@ -405,14 +405,13 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
 	return 0;
 }
 
-void diff_free_filespec_data(struct diff_filespec *s)
+void diff_free_filespec(struct diff_filespec *s)
 {
 	if (s->should_free)
 		free(s->data);
 	else if (s->should_munmap)
 		munmap(s->data, s->size);
-	s->should_free = s->should_munmap = 0;
-	s->data = NULL;
+	free(s);
 }
 
 static void prep_temp_blob(struct diff_tempfile *temp,
@@ -769,8 +768,8 @@ struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
 
 void diff_free_filepair(struct diff_filepair *p)
 {
-	diff_free_filespec_data(p->one);
-	diff_free_filespec_data(p->two);
+	diff_free_filespec(p->one);
+	diff_free_filespec(p->two);
 	free(p);
 }
 
diff --git a/diffcore-break.c b/diffcore-break.c
index 06f9a7f0ee..b0c8461e12 100644
--- a/diffcore-break.c
+++ b/diffcore-break.c
@@ -231,8 +231,8 @@ static void merge_broken(struct diff_filepair *p,
 
 	dp = diff_queue(outq, d->one, c->two);
 	dp->score = p->score;
-	diff_free_filespec_data(d->two);
-	diff_free_filespec_data(c->one);
+	diff_free_filespec(d->two);
+	diff_free_filespec(c->one);
 	free(d);
 	free(c);
 }
diff --git a/diffcore.h b/diffcore.h
index f1b5ca748c..633d1ae5cf 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -43,7 +43,7 @@ extern void fill_filespec(struct diff_filespec *, const unsigned char *,
 			  unsigned short);
 
 extern int diff_populate_filespec(struct diff_filespec *, int);
-extern void diff_free_filespec_data(struct diff_filespec *);
+extern void diff_free_filespec(struct diff_filespec *);
 
 struct diff_filepair {
 	struct diff_filespec *one;
diff --git a/git-commit-script b/git-commit-script
index 24ec446a9d..5e6b877d1b 100755
--- a/git-commit-script
+++ b/git-commit-script
@@ -9,7 +9,7 @@ usage () {
 	die 'git commit [-a]  [-m <message>] [-F <logfile>] [(-C|-c) <commit>] [<path>...]'
 }
 
-all= logfile= use_commit= no_edit= log_given= log_message=
+all= logfile= use_commit= no_edit= log_given= log_message= verify= signoff=
 while case "$#" in 0) break;; esac
 do
   case "$1" in
@@ -64,6 +64,12 @@ do
     use_commit="$1"
     no_edit=t
     shift ;;
+  -s|--s|--si|--sig|--sign|--signo|--signof|--signoff)
+    signoff=t
+    shift ;;
+  -v|--v|--ve|--ver|--veri|--verif|--verify)
+    verify=t
+    shift ;;
   --)
     shift
     break ;;
@@ -86,6 +92,60 @@ t)
 esac
 git-update-cache -q --refresh -- "$@" || exit 1
 
+case "$verify" in
+t)
+	# This is slightly modified from Andrew Morton's Perfect Patch.
+	# Lines you introduce should not have trailing whitespace.
+	# Also check for an indentation that has SP before a TAB.
+	perl -e '
+	    my $fh;
+	    my $found_bad = 0;
+	    my $filename;
+	    my $reported_filename = "";
+	    my $lineno;
+	    sub bad_line {
+		my ($why, $line) = @_;
+		if (!$found_bad) {
+		    print "*\n";
+		    print "* You have some suspicious patch lines:\n";
+		    print "*\n";
+		    $found_bad = 1;
+		}
+		if ($reported_filename ne $filename) {
+		    print "* In $filename\n";
+		    $reported_filename = $filename;
+		}
+		print "* $why (line $lineno)\n$line\n";
+	    }
+	    open $fh, "-|", qw(git-diff-cache -p -M --cached HEAD);
+	    while (<$fh>) {
+		if (m|^diff --git a/(.*) b/\1$|) {
+		    $filename = $1;
+		    next;
+		}
+		if (/^@@ -\S+ \+(\d+)/) {
+		    $lineno = $1 - 1;
+		    next;
+		}
+		if (/^ /) {
+		    $lineno++;
+		    next;
+		}
+		if (s/^\+//) {
+		    $lineno++;
+		    chomp;
+		    if (/\s$/) {
+			bad_line("trailing whitespace", $_);
+		    }
+		    if (/^\s* 	/) {
+			bad_line("indent SP followed by a TAB", $_);
+		    }
+		}
+	    }
+	    exit($found_bad);
+	' || exit ;;
+esac
+
 PARENTS="-p HEAD"
 if [ ! -r "$GIT_DIR/HEAD" ]; then
 	if [ -z "$(git-ls-files)" ]; then
@@ -161,7 +221,14 @@ else
 		export GIT_AUTHOR_DATE
 		git-cat-file commit "$use_commit" |
 		sed -e '1,/^$/d'
-	fi >.editmsg
+	fi |
+	git-stripspace >.editmsg
+	case "$signoff" in
+	t)
+		git-var GIT_COMMITTER_IDENT | sed -e '
+			s/>.*/>/
+			s/^/Signed-off-by: /' >>.editmsg ;;
+	esac
 	git-status-script >>.editmsg
 fi
 if [ "$?" != "0" -a ! -f $GIT_DIR/MERGE_HEAD ]
@@ -176,7 +243,8 @@ case "$no_edit" in
 	;;
 esac
 grep -v '^#' < .editmsg | git-stripspace > .cmitmsg
-if test -s .cmitmsg
+grep -v -i '^Signed-off-by' .cmitmsg >.cmitchk
+if test -s .cmitchk
 then
 	tree=$(git-write-tree) &&
 	commit=$(cat .cmitmsg | git-commit-tree $tree $PARENTS) &&
@@ -187,5 +255,5 @@ else
 	false
 fi
 ret="$?"
-rm -f .cmitmsg .editmsg
+rm -f .cmitmsg .editmsg .cmitchk
 exit "$ret"
diff --git a/git-resolve-script b/git-resolve-script
index 52dd83bae0..4641119e0f 100755
--- a/git-resolve-script
+++ b/git-resolve-script
@@ -6,8 +6,8 @@
 #
 . git-sh-setup-script || die "Not a git archive"
 
-head=$(git-rev-parse --verify "$1")
-merge=$(git-rev-parse --verify "$2")
+head=$(git-rev-parse --verify "$1"^0) || exit
+merge=$(git-rev-parse --verify "$2"^0) || exit
 merge_msg="$3"
 
 dropheads() {
diff --git a/sha1_name.c b/sha1_name.c
index 5d1e441e5a..fdd321448c 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -148,7 +148,7 @@ static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 	};
 	const char **p;
 
-	if (!get_sha1_hex(str, sha1))
+	if (len == 40 && !get_sha1_hex(str, sha1))
 		return 0;
 
 	for (p = prefix; *p; p++) {
@@ -208,13 +208,9 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 	} else
 		parent = -1;
 
-	if (0 <= parent) {
-		ret = get_parent(name, len, sha1, parent);
-		if (!ret)
-			return 0;
-		else if(parent>0)
-			return ret;
-	}
+	if (parent >= 0)
+		return get_parent(name, len, sha1, parent);
+
 	ret = get_sha1_basic(name, len, sha1);
 	if (!ret)
 		return 0;
diff --git a/t/t1100-commit-tree-options.sh b/t/t1100-commit-tree-options.sh
index e59f724f2a..19a0ed4d20 100755
--- a/t/t1100-commit-tree-options.sh
+++ b/t/t1100-commit-tree-options.sh
@@ -32,7 +32,7 @@ test_expect_success \
      GIT_COMMITTER_NAME="Committer Name" \
      GIT_COMMITTER_EMAIL="committer@email" \
      GIT_COMMITTER_DATE="2005-05-26 23:30" \
-     TZ= git-commit-tree `cat treeid` >commitid 2>/dev/null'
+     TZ=GMT git-commit-tree `cat treeid` >commitid 2>/dev/null'
 
 test_expect_success \
     'read commit' \
diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh
index 6d72ed34c1..abce66921c 100755
--- a/t/t5000-tar-tree.sh
+++ b/t/t5000-tar-tree.sh
@@ -41,7 +41,7 @@ test_expect_success \
      find a -type l | xargs git-update-cache --add &&
      treeid=`git-write-tree` &&
      echo $treeid >treeid &&
-     TZ= GIT_COMMITTER_DATE="2005-05-27 22:00:00" \
+     TZ=GMT GIT_COMMITTER_DATE="2005-05-27 22:00:00" \
      git-commit-tree $treeid </dev/null >.git/HEAD'
 
 test_expect_success \
@@ -50,7 +50,7 @@ test_expect_success \
 
 test_expect_success \
     'validate file modification time' \
-    'TZ= tar tvf b.tar a/a |
+    'TZ=GMT tar tvf b.tar a/a |
      awk \{print\ \$4,\ \(length\(\$5\)\<7\)\ ?\ \$5\":00\"\ :\ \$5\} \
      >b.mtime &&
      echo "2005-05-27 22:00:00" >expected.mtime &&