git-p4 has an array of changelists with one label per changelist.
But you can have multiple labels on a single changelist and so this
code fails.
Add a test case demonstrating the problem.
Signed-off-by: Luke Diamand <luke@diamand.org>
Acked-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>