get rid of racy addLink

The remaining callers all did not rely on it checking gitignore, so were
easy to convert.

They were susceptable to the same overwrite race as add and fix,
although less likely to have it and a narrower window than add's race.

Command.Rekey in passing got an unncessary call to removeFile deleted.
addSymlink handles deleting any existing worktree file.

Command/AddUrl.hs

@@ -476,13 +476,13 @@ addWorkTree _ addunlockedmatcher u url file key mtmp = case mtmp of
 		maybeShowJSON $ JSONChunk [("key", serializeKey key)]
 		setUrlPresent key url
 		logChange key u InfoPresent
-		ifM (addAnnexedFile noci addunlockedmatcher file key mtmp)
+		ifM (addAnnexedFile addunlockedmatcher file key mtmp)
 			( do
 				when (isJust mtmp) $
 					logStatus key InfoPresent
 			, maybe noop (\tmp -> pruneTmpWorkDirBefore tmp (liftIO . removeWhenExistsWith R.removeLink)) mtmp
 			)
-	
+
 	-- git does not need to check ignores, because that has already
 	-- been done, as witnessed by the CannAddFile.
 	noci = CheckGitIgnore False