git p4: fix an error message when "p4 where" fails

When "p4 where" fails, for whatever reason, the error message tries to
show an undefined variable.  This minor bug applies only when using a
client spec, and was introduced recently in 9d57c4a (git p4: implement
view spec wildcards with "p4 where", 2013-08-30).

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-p4.py

@@ -1871,7 +1871,7 @@ def update_client_spec_path_cache(self, files):
                 # assume error is "... file(s) not in client view"
                 continue
             if "clientFile" not in res:
-                die("No clientFile from 'p4 where %s'" % depot_path)
+                die("No clientFile in 'p4 where' output")
             if "unmap" in res:
                 # it will list all of them, but only one not unmap-ped
                 continue