git-p4: fix copy detection test

git-p4: fix copy detection test

File file11 is copied from file2 and diff-tree correctly reports
this file as its the source. But it is possible that the diff-tree
algorithm detects file10, which was also copied from file2, as the
origin of the new file.

This fix uses a case statement to support both files as the source
of file11, as was done in other tests in this file.

Signed-off-by: Vitor Antunes <redacted>
Signed-off-by: Junio C Hamano <redacted>