[PATCH 2/7] sequencer: invalidate sequencer state without todo

[Ramkumar Ramachandra <artagnon@gmail.com>]

To check whether an existing sequencer operation is in progress and
error out, we currently check for the existence of the
'.git/sequencer' directory.

  $ git cherry-pick foo..bar
  ... conflict in bar~1 ...
  ... .git/sequencer is created ...
  $ echo "resolved" >problematicfile
  $ git add problematicfile
  $ git commit # Success!
  $ git cherry-pick moo # .git/sequencer exists
  error: A cherry-pick or revert is in progress

Although the sequencer state is useless without '.git/sequencer/todo',
this case never occurs.  However, in the light of the next patch,
where will handle single-commit picks as a special case by not
persisting '.git/sequencer/todo' in the first place, we are forced to
reconsider.  So, when starting a fresh sequencer invocation, remove
the sequencer state carried over from a previous invocation if it's
missing '.git/sequencer/todo'.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 sequencer.c |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 87f146b..8b2518c 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -649,11 +649,15 @@ static void walk_revs_populate_todo(struct replay_insn_list **todo_list,
 
 static int create_seq_dir(void)
 {
+	const char *todo_file = git_path(SEQ_TODO_FILE);
 	const char *seq_dir = git_path(SEQ_DIR);
 
-	if (file_exists(seq_dir))
-		return error(_("%s already exists."), seq_dir);
-	else if (mkdir(seq_dir, 0777) < 0)
+	if (file_exists(todo_file))
+		return error(_("%s already exists."), todo_file);
+
+	/* If todo_file doesn't exist, discard sequencer state */
+	remove_sequencer_state(1);
+	if (mkdir(seq_dir, 0777) < 0)
 		die_errno(_("Could not create sequencer directory '%s'."), seq_dir);
 	return 0;
 }
-- 
1.7.6.351.gb35ac.dirty