refactor getCurrentBranch

Both Command.Sync and Annex.Ingest had their own versions of this.

The one in Annex.Ingest used Git.Branch.currentUnsafe, but does not seem
to need it. That is only checking to see if it's in an adjusted unlocked
branch, and when in an adjusted branch, the branch does in fact exist,
so the added check that Git.Branch.current does is fine.

This commit was sponsored by Denis Dzyubenko on Patreon.

Assistant/Sync.hs

@@ -25,6 +25,7 @@ import qualified Annex.Branch
 import Annex.UUID
 import Annex.TaggedPush
 import Annex.Ssh
+import Annex.CurrentBranch
 import qualified Config
 import Git.Config
 import Config.DynamicConfig
@@ -79,8 +80,7 @@ reconnectRemotes rs = void $ do
 	{- No local branch exists yet, but we can try pulling. -}
 	sync (Nothing, _) = manualPull (Nothing, Nothing) =<< gitremotes
 	go = do
-		(failed, diverged) <- sync
-			=<< liftAnnex (join Command.Sync.getCurrBranch)
+		(failed, diverged) <- sync =<< liftAnnex getCurrentBranch
 		addScanRemotes diverged =<<
 			filterM (not <$$> liftIO . getDynamicConfig . remoteAnnexIgnore . Remote.gitconfig) rs
 		return failed
@@ -127,7 +127,7 @@ pushToRemotes' now remotes = do
 		Annex.Branch.commit =<< Annex.Branch.commitMessage
 		(,,)
 			<$> gitRepo
-			<*> join Command.Sync.getCurrBranch
+			<*> getCurrentBranch
 			<*> getUUID
 	ret <- go True branch g u remotes
 	return ret