dropunused, addunused: Complain when asked to operate on a number that does not correspond to any unused key.

Command/Unused.hs

@@ -351,7 +351,7 @@ startUnused message unused badunused tmpunused maps n = search
 	, (unusedTmpMap maps, tmpunused)
 	]
   where
-	search [] = stop
+	search [] = error $ show n ++ " not valid (run git annex unused for list)"
 	search ((m, a):rest) =
 		case M.lookup n m of
 			Nothing -> search rest

debian/changelog

@@ -28,6 +28,8 @@ git-annex (4.20130628) UNRELEASED; urgency=low
   * Android: gpg is built without --enable-minimal, so it interoperates
     better with other gpg builds that may default to using other algorithms
     for encryption.
+  * dropunused, addunused: Complain when asked to operate on a number that
+    does not correspond to any unused key.
 
  -- Joey Hess <joeyh@debian.org>  Tue, 02 Jul 2013 15:40:55 -0400
 

doc/bugs/git-annex_dropunused_has_no_effect.mdwn

@@ -8,3 +8,5 @@ What can I do to drop all these unused files eating up i-nodes?  Is there a debu
 
 Thanks,
   John
+
+> added a message [[done]] --[[Joey]]