LIB: make deleteDirRecursive more robust

We now try 'deleteDir' first and only start recursive removal
if that fails.

src/HSFM/FileSystem/FileOperations.hs

@@ -71,8 +71,10 @@ import Data.Word
   )
 import Foreign.C.Error
   (
-    eINVAL
+    eEXIST
+  , eINVAL
   , eNOSYS
+  , eNOTEMPTY
   , eXDEV
   )
 import Foreign.C.Types
@@ -416,7 +418,10 @@ deleteDir p = P.withAbsPath p removeDirectory
 --    * not atomic
 --    * examines filetypes explicitly
 deleteDirRecursive :: Path Abs -> IO ()
-deleteDirRecursive p = do
+deleteDirRecursive p =
+  catchErrno [eNOTEMPTY, eEXIST]
+             (deleteDir p)
+    $ do
       files <- getDirsFiles p
       for_ files $ \file -> do
         ftype <- getFileType file