commit: skip already cleared parents in clear_commit_marks_1()

Don't put clean parents on the pending list, as they and their ancestors
don't need any treatment and would be skipped later anyway.  This saves
the allocation and release of a commit list item in ca. 20% of the cases
during a run of the test suite.

Signed-off-by: René Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: rscharfe

commit.c

@@ -693,8 +693,10 @@ static void clear_commit_marks_1(struct commit_list **plist,
 		if (!parents)
 			return;
 
-		while ((parents = parents->next))
-			commit_list_insert(parents->item, plist);
+		while ((parents = parents->next)) {
+			if (parents->item->object.flags & mark)
+				commit_list_insert(parents->item, plist);
+		}
 
 		commit = commit->parents->item;
 	}