t / t5100 / patch0018on commit commit: add short-circuit to paint_down_to_common() (d7c1ec3)
   1diff --git a/foo b/foo
   2index e69de29..d95f3ad 100644
   3--- a/foo
   4+++ b/foo
   5@@ -0,0 +1 @@
   6+content