Add generic 'strbuf_readlink()' helper function

diff --git a/t/t4000-diff-format.sh b/t/t4000-diff-format.sh
index c44b27aeb24816a346f0aa84d70546a0ffd83b2a..6ddd46915d2757bb5a40057e6850a4f72cd4dafb 100755 (executable)
--- a/t/t4000-diff-format.sh
+++ b/t/t4000-diff-format.sh
@@ -7,7 +7,7 @@ test_description='Test built-in diff output engine.
 
 '
 . ./test-lib.sh
-. ../diff-lib.sh
+. "$TEST_DIRECTORY"/diff-lib.sh
 
 echo >path0 'Line 1
 Line 2