Fix directory special remote's cleanup of empty export directories.

Was trying to rmdir the file, which had already been deleted, and when that
failed, it skipped trying to delete the parent directories.

Noticed the bug through testremote, but it can't itself detect such
problems as there is no enumeration in the API.

This commit was sponsored by Brock Spratlen on Patreon.

CHANGELOG

@@ -10,6 +10,7 @@ git-annex (6.20171027) UNRELEASED; urgency=medium
     Thanks, Eric Siegerman 
   * Makefile improvement for BUILDER=stack, use stack to run ghc.
   * testremote: Test exporttree.
+  * Fix directory special remote's cleanup of empty export directories.
 
  -- Joey Hess <id@joeyh.name>  Mon, 30 Oct 2017 12:01:45 -0400
 

Remote/Directory.hs

@@ -276,10 +276,11 @@ renameExportM d _k oldloc newloc = liftIO $ catchBoolIO $ do
 exportPath :: FilePath -> ExportLocation -> FilePath
 exportPath d loc = d </> fromExportLocation loc
 
-{- Removes the ExportLocation directory and its parents, so long as
+{- Removes the ExportLocation's parent directory and its parents, so long as
  - they're empty, up to but not including the topdir. -}
 removeExportLocation :: FilePath -> ExportLocation -> IO ()
-removeExportLocation topdir loc = go (Just $ fromExportLocation loc) (Right ())
+removeExportLocation topdir loc = 
+	go (Just $ takeDirectory $ fromExportLocation loc) (Right ())
   where
 	go _ (Left _e) = return ()
 	go Nothing _ = return ()