t / t5100 / patch0015on commit update-index --split-index: do not split if $GIT_DIR is read only (a0a9675)
   1---
   2diff --git a/foo b/foo
   3index e69de29..d95f3ad 100644
   4--- a/foo
   5+++ b/foo
   6@@ -0,0 +1 @@
   7+content
   8