Bugfix: directory special remote could loop forever storing a key when a too small chunksize was configured.

Ensure that each file has something written to it, even if the bytestring
chunk size is greater than the configured chunksize.

This means we may write a bit larger than the configured value, but only
when the configured value is very small; ie, < 8 kb.

Remote/Directory.hs

@@ -158,7 +158,7 @@ storeSplit' meterupdate chunksize (d:dests) bs c = do
 	feed _ [] _ = return []
 	feed sz (l:ls) h = do
 		let s = fromIntegral $ S.length l
-		if s <= sz
+		if s <= sz || sz == chunksize
 			then do
 				S.hPut h l
 				meterupdate $ toInteger s