made parentDir return a Maybe FilePath; removed most uses of it

parentDir is less safe than takeDirectory, especially when working
with relative FilePaths. It's really only useful in loops that
want to terminate at /

This commit was sponsored by Audric SCHILTKNECHT.

Remote/BitTorrent.hs

@@ -189,7 +189,7 @@ downloadTorrentFile u = do
 		, do
 			showAction "downloading torrent file"
 			showOutput
-			createAnnexDirectory (parentDir torrent)
+			createAnnexDirectory (takeDirectory torrent)
 			if isTorrentMagnetUrl u
 				then do
 					tmpdir <- tmpTorrentDir u

Remote/Directory.hs

@@ -143,7 +143,7 @@ finalizeStoreGeneric :: FilePath -> FilePath -> IO ()
 finalizeStoreGeneric tmp dest = do
 	void $ tryIO $ allowWrite dest -- may already exist
 	void $ tryIO $ removeDirectoryRecursive dest -- or not exist
-	createDirectoryIfMissing True (parentDir dest)
+	createDirectoryIfMissing True (takeDirectory dest)
 	renameDirectory tmp dest
 	-- may fail on some filesystems
 	void $ tryIO $ do

Remote/GCrypt.hs

@@ -315,7 +315,7 @@ store r rsyncopts
 			void $ tryIO $ createDirectoryIfMissing True tmpdir
 			let tmpf = tmpdir </> keyFile k
 			meteredWriteFile p tmpf b
-			let destdir = parentDir $ gCryptLocation r k
+			let destdir = takeDirectory $ gCryptLocation r k
 			Remote.Directory.finalizeStoreGeneric tmpdir destdir
 			return True
 	| Git.repoIsSsh (repo r) = if isShell r
@@ -340,7 +340,7 @@ retrieve r rsyncopts
 remove :: Remote -> Remote.Rsync.RsyncOpts -> Remover
 remove r rsyncopts k
 	| not $ Git.repoIsUrl (repo r) = guardUsable (repo r) (return False) $
-		liftIO $ Remote.Directory.removeDirGeneric (Git.repoLocation (repo r)) (parentDir (gCryptLocation r k))
+		liftIO $ Remote.Directory.removeDirGeneric (Git.repoLocation (repo r)) (takeDirectory (gCryptLocation r k))
 	| Git.repoIsSsh (repo r) = shellOrRsync r removeshell removersync
 	| otherwise = unsupportedUrl
   where

Remote/Git.hs

@@ -556,7 +556,7 @@ rsyncOrCopyFile rsyncparams src dest p =
 	ifM (sameDeviceIds src dest) (docopy, dorsync)
   where
 	sameDeviceIds a b = (==) <$> getDeviceId a <*> getDeviceId b
-	getDeviceId f = deviceID <$> liftIO (getFileStatus $ parentDir f)
+	getDeviceId f = deviceID <$> liftIO (getFileStatus $ takeDirectory f)
 	docopy = liftIO $ bracket
 		(forkIO $ watchfilesize zeroBytesProcessed)
 		(void . tryIO . killThread)

Remote/Rsync.hs

@@ -161,7 +161,7 @@ rsyncSetup mu _ c = do
 store :: RsyncOpts -> Key -> FilePath -> MeterUpdate -> Annex Bool
 store o k src meterupdate = withRsyncScratchDir $ \tmp -> do
 	let dest = tmp </> Prelude.head (keyPaths k)
-	liftIO $ createDirectoryIfMissing True $ parentDir dest
+	liftIO $ createDirectoryIfMissing True $ takeDirectory dest
 	ok <- liftIO $ if canrename
 		then do
 			rename src dest
@@ -214,7 +214,7 @@ remove o k = do
 	 - traverses directories. -}
 	includes = concatMap use annexHashes
 	use h = let dir = h k in
-		[ parentDir dir
+		[ takeDirectory dir
 		, dir
 		-- match content directory and anything in it
 		, dir </> keyFile k </> "***"

Remote/Tahoe.hs

@@ -153,7 +153,7 @@ tahoeConfigure configdir furl mscs = do
 
 createClient :: TahoeConfigDir -> IntroducerFurl -> IO Bool
 createClient configdir furl = do
-	createDirectoryIfMissing True (parentDir configdir)
+	createDirectoryIfMissing True (takeDirectory configdir)
 	boolTahoe configdir "create-client"
 		[ Param "--nickname", Param "git-annex"
 		, Param "--introducer", Param furl