diff --git a/commit.c b/commit.c
index 0431027ef2..593414df36 100644
--- a/commit.c
+++ b/commit.c
@@ -849,9 +849,10 @@ void sort_in_topological_order_fn(struct commit_list ** list, int lifo,
 
 /* merge-rebase stuff */
 
-#define PARENT1 1
-#define PARENT2 2
-#define UNINTERESTING 4
+/* bits #0..7 in revision.h */
+#define PARENT1		(1u<< 8)
+#define PARENT2		(1u<< 9)
+#define UNINTERESTING	(1u<<10)
 
 static struct commit *interesting(struct commit_list *list)
 {
@@ -1080,9 +1081,20 @@ struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2)
 		tmp = next;
 	}
 
-	/* reset flags */
+	return result;
+}
+
+struct commit_list *get_merge_bases_clean(struct commit *rev1,
+                                          struct commit *rev2)
+{
+	unsigned int flags1 = rev1->object.flags;
+	unsigned int flags2 = rev2->object.flags;
+	struct commit_list *result = get_merge_bases(rev1, rev2);
+
 	clear_commit_marks(rev1, PARENT1 | PARENT2 | UNINTERESTING);
 	clear_commit_marks(rev2, PARENT1 | PARENT2 | UNINTERESTING);
+	rev1->object.flags = flags1;
+	rev2->object.flags = flags2;
 
 	return result;
 }
diff --git a/commit.h b/commit.h
index 89b9dad7cc..3a26e29ce6 100644
--- a/commit.h
+++ b/commit.h
@@ -106,5 +106,6 @@ int register_commit_graft(struct commit_graft *, int);
 int read_graft_file(const char *graft_file);
 
 extern struct commit_list *get_merge_bases(struct commit *rev1, struct commit *rev2);
+extern struct commit_list *get_merge_bases_clean(struct commit *rev1, struct commit *rev2);
 
 #endif /* COMMIT_H */