sync: Fix git sync with local git remotes even when they don't have an annex.uuid set.

Catch an exception when ensureInitialized is run in a non-initted
repository. In this case, just read the git config, so that the Git.Repo
object is not LocalUnknown, which is what is used to represent remotes
on eg, drives that are not connected.

The assistant already got this right, and like with the assistant, this
causes an implicit git-annex init of the local remote on the second sync,
once the git-annex branch has been pushed to it.
See this comment for more analysis:
http://git-annex.branchable.com/todo/Recovering_from_a_bad_sync/#comment-64e469a2c1969829ee149cbb41b1c138

This commit was sponsored by jscit.

Remote/Git.hs

@@ -191,20 +191,11 @@ tryGitConfigRead r
 	| Git.repoIsHttp r = store geturlconfig
 	| Git.GCrypt.isEncrypted r = handlegcrypt =<< getConfigMaybe (remoteConfig r "uuid")
 	| Git.repoIsUrl r = return r
-	| otherwise = store $ safely $ do
-		s <- Annex.new r
-		Annex.eval s $ do
-			Annex.BranchState.disableUpdate
-			ensureInitialized
-			Annex.getState Annex.repo
+	| otherwise = store $ liftIO $
+		readlocalannexconfig `catchNonAsync` (const $ Git.Config.read r)
   where
 	haveconfig = not . M.null . Git.config
 
-	-- Reading config can fail due to IO error or
-	-- for other reasons; catch all possible exceptions.
-	safely a = either (const $ return r) return
-			=<< liftIO (try a :: IO (Either SomeException Git.Repo))
-
 	pipedconfig cmd params = do
 		v <- Git.Config.fromPipe r cmd params
 		case v of
@@ -283,6 +274,15 @@ tryGitConfigRead r
 			Just v -> store $ liftIO $ setUUID r $
 				genUUIDInNameSpace gCryptNameSpace v
 
+	{- Throws an exception if the remote is not already initialied
+	 - or cannot be automatically initialized. -}
+	readlocalannexconfig = do
+		s <- Annex.new r
+		Annex.eval s $ do
+			Annex.BranchState.disableUpdate
+			ensureInitialized
+			Annex.getState Annex.repo
+
 {- Checks if a given remote has the content for a key inAnnex.
  - If the remote cannot be accessed, or if it cannot determine
  - whether it has the content, returns a Left error message.