Make --with-origin also work without origin :)

Signed-off-by: Simon Hausmann <shausman@trolltech.com>

contrib/fast-import/git-p4

@@ -846,8 +846,9 @@ class P4Sync(Command):
             self.refPrefix = "refs/heads/"
 
         if self.syncWithOrigin:
-            print "Syncing with origin first as requested by calling git fetch origin"
-            system("git fetch origin")
+            if gitBranchExists("origin"):
+                print "Syncing with origin first as requested by calling git fetch origin"
+                system("git fetch origin")
 
         createP4HeadRef = False;