Merge branch 'da/mergetool-delete-delete-conflict' into maint

"git mergetool" did not work well with conflicts that both sides
deleted.

* da/mergetool-delete-delete-conflict:
  mergetool: honor tempfile configuration when resolving delete conflicts
  mergetool: support delete/delete conflicts

git-mergetool.sh

@@ -126,7 +126,12 @@ resolve_deleted_merge () {
 		case "$ans" in
 		[mMcC]*)
 			git add -- "$MERGED"
-			cleanup_temp_files --save-backup
+			if test "$merge_keep_backup" = "true"
+			then
+				cleanup_temp_files --save-backup
+			else
+				cleanup_temp_files
+			fi
 			return 0
 			;;
 		[dD]*)
@@ -135,6 +140,10 @@ resolve_deleted_merge () {
 			return 0
 			;;
 		[aA]*)
+			if test "$merge_keep_temporaries" = "false"
+			then
+				cleanup_temp_files
+			fi
 			return 1
 			;;
 		esac
@@ -282,8 +291,14 @@ merge_file () {
 		return
 	fi
 
-	mv -- "$MERGED" "$BACKUP"
-	cp -- "$BACKUP" "$MERGED"
+	if test -f "$MERGED"
+	then
+		mv -- "$MERGED" "$BACKUP"
+		cp -- "$BACKUP" "$MERGED"
+	fi
+	# Create a parent directory to handle delete/delete conflicts
+	# where the base's directory no longer exists.
+	mkdir -p "$(dirname "$MERGED")"
 
 	checkout_staged_file 1 "$MERGED" "$BASE"
 	checkout_staged_file 2 "$MERGED" "$LOCAL"
@@ -295,7 +310,9 @@ merge_file () {
 		describe_file "$local_mode" "local" "$LOCAL"
 		describe_file "$remote_mode" "remote" "$REMOTE"
 		resolve_deleted_merge
-		return
+		status=$?
+		rmdir -p "$(dirname "$MERGED")" 2>/dev/null
+		return $status
 	fi
 
 	if is_symlink "$local_mode" || is_symlink "$remote_mode"

t/t7610-mergetool.sh

@@ -243,6 +243,70 @@ test_expect_success 'mergetool takes partial path' '
 	git reset --hard
 '
 
+test_expect_success 'mergetool delete/delete conflict' '
+	git checkout -b delete-base branch1 &&
+	mkdir -p a/a &&
+	(echo one; echo two; echo 3; echo 4) >a/a/file.txt &&
+	git add a/a/file.txt &&
+	git commit -m"base file" &&
+	git checkout -b move-to-b delete-base &&
+	mkdir -p b/b &&
+	git mv a/a/file.txt b/b/file.txt &&
+	(echo one; echo two; echo 4) >b/b/file.txt &&
+	git commit -a -m"move to b" &&
+	git checkout -b move-to-c delete-base &&
+	mkdir -p c/c &&
+	git mv a/a/file.txt c/c/file.txt &&
+	(echo one; echo two; echo 3) >c/c/file.txt &&
+	git commit -a -m"move to c" &&
+	test_must_fail git merge move-to-b &&
+	echo d | git mergetool a/a/file.txt &&
+	! test -f a/a/file.txt &&
+	git reset --hard HEAD &&
+	test_must_fail git merge move-to-b &&
+	echo m | git mergetool a/a/file.txt &&
+	test -f b/b/file.txt &&
+	git reset --hard HEAD &&
+	test_must_fail git merge move-to-b &&
+	! echo a | git mergetool a/a/file.txt &&
+	! test -f a/a/file.txt &&
+	git reset --hard HEAD
+'
+
+test_expect_success 'mergetool produces no errors when keepBackup is used' '
+	test_config mergetool.keepBackup true &&
+	test_must_fail git merge move-to-b &&
+	: >expect &&
+	echo d | git mergetool a/a/file.txt 2>actual &&
+	test_cmp expect actual &&
+	! test -d a &&
+	git reset --hard HEAD
+'
+
+test_expect_success 'mergetool honors tempfile config for deleted files' '
+	test_config mergetool.keepTemporaries false &&
+	test_must_fail git merge move-to-b &&
+	echo d | git mergetool a/a/file.txt &&
+	! test -d a &&
+	git reset --hard HEAD
+'
+
+test_expect_success 'mergetool keeps tempfiles when aborting delete/delete' '
+	test_config mergetool.keepTemporaries true &&
+	test_must_fail git merge move-to-b &&
+	! (echo a; echo n) | git mergetool a/a/file.txt &&
+	test -d a/a &&
+	cat >expect <<-\EOF &&
+	file_BASE_.txt
+	file_LOCAL_.txt
+	file_REMOTE_.txt
+	EOF
+	ls -1 a/a | sed -e "s/[0-9]*//g" >actual &&
+	test_cmp expect actual &&
+	git clean -fdx &&
+	git reset --hard HEAD
+'
+
 test_expect_success 'deleted vs modified submodule' '
 	git checkout -b test6 branch1 &&
 	git submodule update -N &&