--- a/tests/test-diffdir
+++ b/tests/test-diffdir
@@ -12,3 +12,7 @@ hg diff | sed -e "s/\(+++ [a-zA-Z0-9_/.-
 
 hg diff -r tip | sed -e "s/\(+++ [a-zA-Z0-9_/.-]*\).*/\1/" \
                      -e "s/\(--- [a-zA-Z0-9_/.-]*\).*/\1/"
+
+echo foo > a
+hg diff | sed -e "s/\(+++ [a-zA-Z0-9_/.-]*\).*/\1/" \
+              -e "s/\(--- [a-zA-Z0-9_/.-]*\).*/\1/"