fix variable usage (oops)

Signed-off-by: Simon Hausmann <simon@lst.de>
diff --git a/contrib/fast-import/git-p4 b/contrib/fast-import/git-p4
index 28b0885..72fa48a 100755
--- a/contrib/fast-import/git-p4
+++ b/contrib/fast-import/git-p4
@@ -808,7 +808,7 @@
         self.labels = {}
 
         l = p4CmdList("labels %s..." % self.globalPrefix)
-        if len(l) > 0 and not silent:
+        if len(l) > 0 and not self.silent:
             print "Finding files belonging to labels in %s" % self.globalPrefix
 
         for output in l: