Limiting the number of copies per trustlevel

The --copies flag now takes an argument of the form:
  trustlevel:number or number

If a trust level is specified the command is limited to files
with at least 'number' copies of this 'trustlevel'.

Limit.hs

@@ -16,6 +16,7 @@ import qualified Utility.Matcher
 import qualified Remote
 import qualified Backend
 import Annex.Content
+import Logs.Trust
 
 type Limit = Utility.Matcher.Token (FilePath -> Annex Bool)
 
@@ -83,16 +84,21 @@ addIn name = addLimit $ check $ if name == "." then inAnnex else inremote
 {- Adds a limit to skip files not believed to have the specified number
  - of copies. -}
 addCopies :: String -> Annex ()
-addCopies num =
-	case readish num :: Maybe Int of
-		Nothing -> error "bad number for --copies"
-		Just n -> addLimit $ check n
-	where
+addCopies trust_num = addLimit . check $ readnum num
+	where   (num, mayCheckTrust) =
+	          case split ":" trust_num of
+                    [trust, num'] -> (num', checkTrust (readtrust trust))
+                    [num']        -> (num', const (return True))
+                    _             -> bad
+	        readnum = maybe bad id . readish
+	        readtrust = maybe bad id . readTrust
 		check n = Backend.lookupFile >=> handle n
 		handle _ Nothing = return False
 		handle n (Just (key, _)) = do
-			us <- Remote.keyLocations key
+			us <- filterM mayCheckTrust =<< Remote.keyLocations key
 			return $ length us >= n
+	        checkTrust t u = (== t) <$> lookupTrust u -- == or >=
+	        bad = error "bad number or trust:number for --copies"
 
 {- Adds a limit to skip files not using a specified key-value backend. -}
 addInBackend :: String -> Annex ()