Msysgit testing showed that the source file found by copy
detection is indeterminate when there are multiple sources
to choose from. This appears to be valid. Adjust the test
so that it passes if it finds any of the potential copy sources.
Signed-off-by: Pete Wyckoff <pw@padd.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>