git am --abort

After failing to apply patches in the middle of a series, "git am --abort"
lets you go back to the original commit.

[jc: doc/help update from Olivier, and fixups for "am -3" squashed in]

Signed-off-by: Nanako Shiraishi <nanako3@lavabit.com>
Signed-off-by: Olivier Marin <dkr@freesurf.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-am.txt

@@ -13,7 +13,7 @@ SYNOPSIS
          [--3way] [--interactive] [--binary]
          [--whitespace=<option>] [-C<n>] [-p<n>]
 	 [<mbox> | <Maildir>...]
-'git am' (--skip | --resolved)
+'git am' (--skip | --resolved | --abort)
 
 DESCRIPTION
 -----------
@@ -99,6 +99,9 @@ default.   You could use `--no-utf8` to override this.
 	or `--skip` to handle the failure.  This is solely
 	for internal use between 'git-rebase' and 'git-am'.
 
+--abort::
+	Restore the original branch and abort the patching operation.
+
 DISCUSSION
 ----------
 

git-am.sh

@@ -22,6 +22,7 @@ p=              pass it through git-apply
 resolvemsg=     override error message when patch failure occurs
 r,resolved      to be used after a patch failure
 skip            skip the current patch
+abort           restore the original branch and abort the patching operation.
 rebasing        (internal use for git-rebase)"
 
 . git-sh-setup
@@ -54,6 +55,7 @@ stop_here_user_resolve () {
     fi
     echo "When you have resolved this problem run \"$cmdline --resolved\"."
     echo "If you would prefer to skip this patch, instead run \"$cmdline --skip\"."
+    echo "To restore the original branch and stop patching run \"$cmdline --abort\"."
 
     stop_here $1
 }
@@ -120,7 +122,7 @@ It does not apply to blobs recorded in its index."
 
 prec=4
 dotest="$GIT_DIR/rebase"
-sign= utf8=t keep= skip= interactive= resolved= binary= rebasing=
+sign= utf8=t keep= skip= interactive= resolved= binary= rebasing= abort=
 resolvemsg= resume=
 git_apply_opt=
 
@@ -145,6 +147,8 @@ do
 		resolved=t ;;
 	--skip)
 		skip=t ;;
+	--abort)
+		abort=t ;;
 	--rebasing)
 		rebasing=t threeway=t keep=t binary=t ;;
 	-d|--dotest)
@@ -177,7 +181,7 @@ fi
 
 if test -d "$dotest"
 then
-	case "$#,$skip$resolved" in
+	case "$#,$skip$resolved$abort" in
 	0,*t*)
 		# Explicit resume command and we do not have file, so
 		# we are happy.
@@ -197,9 +201,18 @@ then
 	esac ||
 	die "previous rebase directory $dotest still exists but mbox given."
 	resume=yes
+
+	case "$abort" in
+	t)
+		git rerere clear
+		git read-tree --reset -u HEAD ORIG_HEAD
+		git reset ORIG_HEAD
+		rm -fr "$dotest"
+		exit ;;
+	esac
 else
-	# Make sure we are not given --skip nor --resolved
-	test ",$skip,$resolved," = ,,, ||
+	# Make sure we are not given --skip, --resolved, nor --abort
+	test "$skip$resolved$abort" = "" ||
 		die "Resolve operation not in progress, we are not resuming."
 
 	# Start afresh.

t/t4151-am-abort.sh

@@ -0,0 +1,56 @@
+#!/bin/sh
+
+test_description='am --abort'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	for i in a b c d e f g
+	do
+		echo $i
+	done >file-1 &&
+	cp file-1 file-2 &&
+	test_tick &&
+	git add file-1 file-2 &&
+	git commit -m initial &&
+	git tag initial &&
+	for i in 2 3 4 5
+	do
+		echo $i >>file-1 &&
+		test_tick &&
+		git commit -a -m $i || break
+	done &&
+	git format-patch initial &&
+	git checkout -b side initial &&
+	echo local change >file-2-expect
+'
+
+for with3 in '' ' -3'
+do
+	test_expect_success "am$with3 stops at a patch that does not apply" '
+
+		git reset --hard initial &&
+		cp file-2-expect file-2 &&
+
+		test_must_fail git am$with3 000[124]-*.patch &&
+		git log --pretty=tformat:%s >actual &&
+		for i in 3 2 initial
+		do
+			echo $i
+		done >expect &&
+		test_cmp expect actual
+	'
+
+	test_expect_success "am --abort goes back after failed am$with3" '
+		git-am --abort &&
+		git rev-parse HEAD >actual &&
+		git rev-parse initial >expect &&
+		test_cmp expect actual &&
+		test_cmp file-2-expect file-2 &&
+		git diff-index --exit-code --cached HEAD &&
+		test ! -f .git/rr-cache/MERGE_RR
+	'
+
+done
+
+test_done