Re: [PATCH 1/2] am: handle stray $dotest directory

The following bug has been observed:

  $ git am  # no input file
  ^C
  $ git am --abort
  Resolve operation not in progress, we are not resuming.

This happens because the following test fails:

  test -d "$dotest" && test -f "$dotest/last" && test -f "$dotest/next"

and the codepath for an "am in-progress" is not executed.  It falls back
to the codepath that treats this as a "fresh execution".  Before
rr/rebase-autostash, this condition was

  test -d "$dotest"

It would incorrectly execute the "normal" am --abort codepath:

  git read-tree --reset -u HEAD ORIG_HEAD
  git reset ORIG_HEAD

by incorrectly assuming that an am is "in progress" (i.e. ORIG_HEAD
etc. was written during the previous execution).

Notice that

  $ git am
  ^C

executes nothing of significance, is equivalent to

  $ mkdir .git/rebase-apply

Therefore, the correct solution is to treat .git/rebase-apply as a
"stray directory" and remove it on --abort in the fresh-execution
codepath.

While at it, tell the user to run "git am --abort" to get rid of the
stray $dotest directory, if she attempts anything else.

Reported-by: Junio C Hamano <redacted>
Signed-off-by: Ramkumar Ramachandra <redacted>
---
 git-am.sh     | 14 ++++++++++++++
 t/t4150-am.sh |  6 ++++++
 2 files changed, 20 insertions(+)

diff --git a/git-am.sh b/git-am.sh
index 1cf3d1d..37ee18b 100755
--- a/git-am.sh
+++ b/git-am.sh

@@ -506,6 +506,20 @@ then
 	esac
 	rm -f "$dotest/dirtyindex"
 else
+	# Possible stray $dotest directory
+	if test -d "$dotest"; then
+	case "$skip,$resolved,$abort" in
+		,,t)
+			rm -fr "$dotest"
+			exit 0
+			;;
+		*)
+			die "$(eval_gettext "Stray $dotest directory found.
+Use \"git am --abort\" to remove it.")"
+			;;
+	esac

+	fi
+
 	# Make sure we are not given --skip, --resolved, nor --abort
 	test "$skip$resolved$abort" = "" ||
 		die "$(gettext "Resolve operation not in progress, we are not resuming.")"

diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index 12f6b02..6c2cc3e 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh

@@ -363,6 +363,12 @@ test_expect_success 'am --skip works' '
 	test_cmp expected another
 '
 
+test_expect_success 'am --abort removes a stray directory' '
+	mkdir .git/rebase-apply &&
+	git am --abort &&
+	test_path_is_missing .git/rebase-apply
+'
+
 test_expect_success 'am --resolved works' '
 	echo goodbye >expected &&
 	rm -fr .git/rebase-apply &&