tests: use 'test_must_be_empty' instead of 'test_cmp <empty> <out>'

[git] / t / t4135 / git-with spaces.diff

diff --git a/post image.txt b/post image.txt
new file mode 100644
index 0000000..eff0c54
--- /dev/null
+++ b/post image.txt    
@@ -0,0 +1 @@
+postimage