If base is already matched, skip that part when calling
fnmatch(). This happens quite often if users start a command from
worktree's subdirectory and prefix is usually prepended to all
pathspecs.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>