addurl: Refuse to overwrite any existing, non-annexed file.

Command/AddUrl.hs

@@ -259,6 +259,7 @@ performQuvi relaxed pageurl videourl file = ifAnnexed file addurl geturl
 #ifdef WITH_QUVI
 addUrlFileQuvi :: Bool -> URLString -> URLString -> FilePath -> Annex (Maybe Key)
 addUrlFileQuvi relaxed quviurl videourl file = do
+	checkDoesNotExist file
 	let key = Backend.URL.fromUrl quviurl Nothing
 	ifM (pure relaxed <||> Annex.getState Annex.fast)
 		( do
@@ -309,12 +310,19 @@ addUrlChecked relaxed url u checkexistssize key
 
 addUrlFile :: Bool -> URLString -> Url.UrlInfo -> FilePath -> Annex (Maybe Key)
 addUrlFile relaxed url urlinfo file = do
+	checkDoesNotExist file
 	liftIO $ createDirectoryIfMissing True (parentDir file)
 	ifM (Annex.getState Annex.fast <||> pure relaxed)
 		( nodownload url urlinfo file
 		, downloadWeb url urlinfo file
 		)
 
+checkDoesNotExist :: FilePath -> Annex ()
+checkDoesNotExist file = go =<< liftIO (catchMaybeIO $ getSymbolicLinkStatus file)
+  where
+	go Nothing = return ()
+	go (Just _) = error $ file ++ " already exists and is not annexed; not overwriting"
+
 downloadWeb :: URLString -> Url.UrlInfo -> FilePath -> Annex (Maybe Key)
 downloadWeb url urlinfo file = do
 	let dummykey = addSizeUrlKey urlinfo $ Backend.URL.fromUrl url Nothing

debian/changelog

@@ -35,6 +35,7 @@ git-annex (6.20151219) UNRELEASED; urgency=medium
     modified the same as typechanged files.
   * addurl: Added --batch and --with-files options.
   * addurl: Support --json, particularly useful in --batch mode.
+  * addurl: Refuse to overwrite any existing, non-annexed file.
   * Debian: Adjust build dependencies for webapp, DAV. Now available on
     mips, mipsel, but temporarily removed armel since build is failing
     there.

doc/bugs/addurl_--file__causes_file_redownload_even_if_it_already_present.mdwn

@@ -25,3 +25,8 @@ git-annex version: 6.20160104+gitg0cf96be-1~ndall+1
 """]
 
 [[!meta author=yoh]]
+
+> I don't think that the re-download is the bug. The actual problem
+> is that the file is present and not an annexed file, so git-annex addurl
+> should avoid overwriting it, whatever its content. [[fixed|done]]
+> --[[Joey]]