t5303: Do not overwrite an existing pack
This test corrupts a pack file, then repacks the objects. The consequence
is that the repacked pack file has the same name as the original file
(that has been corrupted).
During its operation, git-pack-objects opens the corrupted file and keeps
it open at all times. On Windows, this is a problem because a file that is
open in any process cannot be delete or replaced, but that is what we do
in some of the test cases, and so they fail.
The work-around is to write the repacked objects to a file of a different
name, and replace the original after git-pack-objects has terminated.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>