[PATCH] revision: honor --exclude-first-parent-only with SEEN first parent

The '--exclude-first-parent-only' option instructs the revision
walker to follow only the first parent of a merge commit to
propagate down the UNINTERESTING bit.

However, if the first parent has already been marked SEEN (for
example, because it was explicitly specified on the command line),
process_parents() skips it with a 'continue' statement.  But the
loop then continues on to process the second parent, because the
check for the '--exclude-first-parent-only' option is near the end
of the loop, which the 'continue' statement skips.  Consequently, we
end up marking the second parent as UNINTERESTING.

Break out of the loop instead of continuing when the first parent is
already SEEN or fails to parse.  This ensures that we do not process
subsequent parents and mark them as UNINTERESTING.

Signed-off-by: Junio C Hamano <[email protected]>
Reviewed-by: Jerry Zhang <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
---

 * This time with a commit log message.

 revision.c                   | 10 ++++++++--
 t/t6012-rev-list-simplify.sh | 18 ++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/revision.c b/revision.c
index 599b3a66c3..9b30663669 100644
--- a/revision.c
+++ b/revision.c
@@ -1152,12 +1152,18 @@ static int process_parents(struct rev_info *revs, struct commit *commit,
 			if (p)
 				p->object.flags |= UNINTERESTING |
 						   CHILD_VISITED;
-			if (repo_parse_commit_gently(revs->repo, p, 1) < 0)
+			if (repo_parse_commit_gently(revs->repo, p, 1) < 0) {
+				if (revs->exclude_first_parent_only)
+					break;
 				continue;
+			}
 			if (p->parents)
 				mark_parents_uninteresting(revs, p);
-			if (p->object.flags & SEEN)
+			if (p->object.flags & SEEN) {
+				if (revs->exclude_first_parent_only)
+					break;
 				continue;
+			}
 			p->object.flags |= (SEEN | NOT_USER_GIVEN);
 			if (list)
 				commit_list_insert_by_date(p, list);
diff --git a/t/t6012-rev-list-simplify.sh b/t/t6012-rev-list-simplify.sh
index 4cecb6224c..2284bbba12 100755
--- a/t/t6012-rev-list-simplify.sh
+++ b/t/t6012-rev-list-simplify.sh
@@ -285,4 +285,22 @@ test_expect_success 'log --graph --simplify-merges --show-pulls' '
 	test_cmp expect actual
 '
 
+test_expect_success 'exclude-first-parent-only with parent already seen' '
+	git checkout --orphan test-seen &&
+	git rm -rf . &&
+	test_commit r1 &&
+	git checkout -b branch-f &&
+	test_commit f &&
+	git checkout test-seen &&
+	git merge --no-ff --no-edit -m r2 branch-f &&
+	git tag r2 &&
+
+	git rev-list --exclude-first-parent-only f ^r2 >actual &&
+	git rev-parse f >expect &&
+	test_cmp expect actual &&
+
+	git rev-list --exclude-first-parent-only f r1 ^r2 >actual2 &&
+	test_cmp expect actual2
+'
+
 test_done
-- 
2.55.0-496-g61638ae030