t5604: make hash independent

t5604: make hash independent

To make our values hash independent, we turn the directory of the object
into "Y" and the file name into "Z" after having sorted items by their
name. However, when using SHA-256, one of our file names begins with an
"a" character, which means it sorts into the wrong place in the list,
causing the test to fail.

Since we don't care about the order of these items, just sort them after
stripping actual hash contents, which means they'll work with any hash
algorithm.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>