Fix git rebase --continue to work with touched files

When performing a non-interactive rebase, sometimes
"git rebase --continue" will fail if an unmodified file is
touched in the working directory:

    You must edit all merge conflicts and then
    mark them as resolved using git add

This is caused by "git diff-files" reporting a difference
between the index and the filesystem:

    :100644 100644 d00491...... 000000...... M	file

The fix is to run "git update-index --refresh" before
"git diff-files" as is done in git-rebase--interactive.

Signed-off-by: David D. Kilzer <ddkilzer@kilzer.net>
Acked-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase.sh

@@ -208,6 +208,7 @@ do
 		test -d "$dotest" -o -d "$GIT_DIR"/rebase-apply ||
 			die "No rebase in progress?"
 
+		git update-index --ignore-submodules --refresh &&
 		git diff-files --quiet --ignore-submodules || {
 			echo "You must edit all merge conflicts and then"
 			echo "mark them as resolved using git add"

t/t3418-rebase-continue.sh

@@ -0,0 +1,43 @@
+#!/bin/sh
+
+test_description='git rebase --continue tests'
+
+. ./test-lib.sh
+
+. "$TEST_DIRECTORY"/lib-rebase.sh
+
+set_fake_editor
+
+test_expect_success 'setup' '
+	test_commit "commit-new-file-F1" F1 1 &&
+	test_commit "commit-new-file-F2" F2 2 &&
+
+	git checkout -b topic HEAD^ &&
+	test_commit "commit-new-file-F2-on-topic-branch" F2 22 &&
+
+	git checkout master
+'
+
+test_expect_success 'interactive rebase --continue works with touched file' '
+	rm -fr .git/rebase-* &&
+	git reset --hard &&
+	git checkout master &&
+
+	FAKE_LINES="edit 1" git rebase -i HEAD^ &&
+	test-chmtime =-60 F1 &&
+	git rebase --continue
+'
+
+test_expect_success 'non-interactive rebase --continue works with touched file' '
+	rm -fr .git/rebase-* &&
+	git reset --hard &&
+	git checkout master &&
+
+	test_must_fail git rebase --onto master master topic &&
+	echo "Resolved" >F2 &&
+	git add F2 &&
+	test-chmtime =-60 F1 &&
+	git rebase --continue
+'
+
+test_done