fix real underlaying cause, and fix test suite to not skip it

Backend.hs

@@ -130,7 +130,6 @@ lookupFile file = do
 		getsymlink = do
 			l <- readSymbolicLink file
 			return $ takeFileName l
-		makekey _ [] = return Nothing
 		makekey bs l = do
 			case maybeLookupBackendName bs bname of
 				Nothing -> do

TypeInternals.hs

@@ -55,7 +55,7 @@ instance Read Key where
 	readsPrec _ s = [(Key (b,k), "")]
 		where
 			l = split ":" s
-			b = head l
+			b = if null l then "" else head l
 			k = join ":" $ drop 1 l
 
 -- for quickcheck
@@ -67,13 +67,9 @@ instance Arbitrary Key where
 
 prop_idempotent_key_read_show :: Key -> Bool
 prop_idempotent_key_read_show k
-	-- filter out empty key or backend names
-	-- also backend names will not contain colons
-	| null kname || null bname || elem ':' bname = True
+	-- backend names will never contain colons
+	| elem ':' (backendName k) = True
 	| otherwise = k == (read $ show k)
-	where
-		bname = backendName k
-		kname = keyName k
 
 backendName :: Key -> BackendName
 backendName (Key (b,_)) = b

debian/changelog

@@ -4,8 +4,7 @@ git-annex (0.17) unstable; urgency=low
     it being an error.
   * New migrate subcommand can be used to switch files to using a different
     backend, safely and with no duplication of content.
-  * bugfix: Fix crash caused by a symlink in the repo with link text ending in
-    a "/". (Thanks Henrik for reporting.)
+  * bugfix: Fix crash caused by empty key name. (Thanks Henrik for reporting.)
 
  -- Joey Hess <joeyh@debian.org>  Sun, 09 Jan 2011 10:04:11 -0400