mq: handle deleting the same patch twice in one command (issue2427)

hgext/mq.py

@@ -765,7 +765,8 b' class queue(object):'
                 raise util.Abort(_("cannot delete applied patch %s") % patch)
             if patch not in self.series:
                 raise util.Abort(_("patch %s not in series file") % patch)
-            realpatches.append(patch)
+            if patch not in realpatches:
+                realpatches.append(patch)
 
         numrevs = 0
         if opts.get('rev'):

tests/test-mq-qdelete.t

@@ -24,7 +24,9 b''
   popping c
   now at: b
 
-  $ hg qdel c
+Delete the same patch twice in one command (issue2427)
+
+  $ hg qdel c c
 
   $ hg qseries
   a