better handling of overwriting an existing file/directory/broken link when importing

Previous test did not notice if there is a dangling symlink.

Also, if a directory exists with the same name as the imported file, that
cannot work, so don't let --force have an effect.

Command/Import.hs

@@ -88,16 +88,20 @@ start mode (srcfile, destfile) =
 		liftIO $ removeFile srcfile
 		next $ return True
 	importfile = do
-		whenM (liftIO $ doesFileExist destfile) $
-			unlessM (Annex.getState Annex.force) $
-				error $ "not overwriting existing " ++ destfile ++
-					" (use --force to override)"
-	
+		handleexisting =<< liftIO (catchMaybeIO $ getSymbolicLinkStatus destfile)
 		liftIO $ createDirectoryIfMissing True (parentDir destfile)
 		liftIO $ if mode == Duplicate || mode == SkipDuplicates
 			then void $ copyFileExternal srcfile destfile
 			else moveFile srcfile destfile
 		Command.Add.perform destfile
+	handleexisting Nothing = noop
+	handleexisting (Just s)
+		| isDirectory s = notoverwriting "(is a directory)"
+		| otherwise = ifM (Annex.getState Annex.force) $
+			( liftIO $ nukeFile destfile
+			, notoverwriting "(use --force to override)"
+			)
+	notoverwriting why = error $ "not overwriting existing " ++ destfile ++ " " ++ why
 	pickaction isdup = case mode of
 		DeDuplicate
 			| isdup -> Just deletedup

debian/changelog

@@ -17,6 +17,8 @@ git-annex (5.20131131) UNRELEASED; urgency=low
   * import: Add --skip-duplicates option.
   * Windows: watch and assistant work! (very experimental)
   * lock: Require --force. Closes: #731606
+  * import: better handling of overwriting an existing file/directory/broken
+    link when importing
 
  -- Joey Hess <joeyh@debian.org>  Sun, 01 Dec 2013 13:57:58 -0400