[PATCH 16/18] revert: Remove sequencer state when no commits are pending

[Ramkumar Ramachandra <artagnon@gmail.com>]

When cherry-pick or revert is called on a list of commits, and a
conflict encountered somewhere in the middle, the data in
".git/sequencer" is required to continue the operation.  However, when
a conflict is encountered in the very last commit, the user will have
to "continue" after resolving the conflict and committing just so that
the sequencer state is removed.  This is how the current "rebase -i"
script works as well.

$ git cherry-pick foo..bar
... conflict encountered while picking "bar" ...
$ echo "resolved" >problematicfile
$ git add problematicfile
$ git commit
$ git cherry-pick --continue # This would be a noop

Change this so that the sequencer state is cleared when a conflict is
encountered in the last commit.  Incidentally, this patch makes sure
that some existing tests don't break when features like "--reset" and
"--continue" are implemented later in the series.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/revert.c                |   12 +++++++++++-
 t/t3510-cherry-pick-sequence.sh |   24 ++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletions(-)

diff --git a/builtin/revert.c b/builtin/revert.c
index 3c792fa..09d479b 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -887,8 +887,18 @@ static int pick_commits(struct commit_list *todo_list, struct replay_opts *opts)
 	for (cur = todo_list; cur; cur = cur->next) {
 		save_todo(cur, opts);
 		res = do_pick_commit(cur->item, opts);
-		if (res)
+		if (res) {
+			if (!cur->next)
+				/*
+				 * An error was encountered while
+				 * picking the last commit; the
+				 * sequencer state is useless now --
+				 * the user simply needs to resolve
+				 * the conflict and commit
+				 */
+				remove_sequencer_state(0);
 			return res;
+		}
 	}
 
 	/*
diff --git a/t/t3510-cherry-pick-sequence.sh b/t/t3510-cherry-pick-sequence.sh
index aea4f6c..428b5bf 100755
--- a/t/t3510-cherry-pick-sequence.sh
+++ b/t/t3510-cherry-pick-sequence.sh
@@ -83,4 +83,28 @@ test_expect_success '--reset cleans up sequencer state' '
 	test_path_is_missing .git/sequencer
 '
 
+test_expect_success 'cherry-pick cleans up sequencer state when one commit is left' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick base..picked &&
+	test_path_is_missing .git/sequencer &&
+	echo "resolved" >foo &&
+	git add foo &&
+	git commit &&
+	{
+		git rev-list HEAD |
+		git diff-tree --root --stdin |
+		sed "s/$_x40/OBJID/g"
+	} >actual &&
+	cat >expect <<-\EOF &&
+	OBJID
+	:100644 100644 OBJID OBJID M	foo
+	OBJID
+	:100644 100644 OBJID OBJID M	unrelated
+	OBJID
+	:000000 100644 OBJID OBJID A	foo
+	:000000 100644 OBJID OBJID A	unrelated
+	EOF
+	test_cmp expect actual
+'
+
 test_done
-- 
1.7.4.rc1.7.g2cf08.dirty