avoid double commit during transition

The second commit had some bad refs which resulted in the race detection
code running. But that commit was unnecessary anyway, it only was there to
merge in the other refs.

Annex/Branch.hs

@@ -162,17 +162,13 @@ updateTo pairs = do
 			showSideAction merge_desc
 			mergeIndex refs
 		let commitrefs = nub $ fullname:refs
-		transitioned <- handleTransitions localtransitions commitrefs
-		case transitioned of
-			Nothing -> do
-				ff <- if dirty
-					then return False
-					else inRepo $ Git.Branch.fastForward fullname refs
-				if ff
-					then updateIndex branchref
-					else commitBranch branchref merge_desc commitrefs
-			Just (branchref', commitrefs') ->
-				commitBranch branchref' merge_desc commitrefs'
+		unlessM (handleTransitions localtransitions commitrefs) $ do
+			ff <- if dirty
+				then return False
+				else inRepo $ Git.Branch.fastForward fullname refs
+			if ff
+				then updateIndex branchref
+				else commitBranch branchref merge_desc commitrefs
 		liftIO cleanjournal
 
 {- Gets the content of a file, which may be in the journal, or in the index
@@ -251,7 +247,8 @@ commitBranch' branchref message parents = do
 	committedref <- inRepo $ Git.Branch.commit message fullname parents
 	setIndexSha committedref
 	parentrefs <- commitparents <$> catObject committedref
-	when (racedetected branchref parentrefs) $
+	when (racedetected branchref parentrefs) $ do
+		liftIO $ print ("race detected", branchref, parentrefs, "committing", (branchref, parents))
 		fixrace committedref parentrefs
   where
 	-- look for "parent ref" lines and return the refs
@@ -394,34 +391,33 @@ stageJournal = withIndex $ do
 
 {- This is run after the refs have been merged into the index,
  - but before the result is committed to the branch.
- - Which is why it's passed the contents of the local branches's
- - transition log before that merge took place.
+ - (Which is why it's passed the contents of the local branches's
+ - transition log before that merge took place.)
  -
  - When the refs contain transitions that have not yet been done locally,
  - the transitions are performed on the index, and a new branch
- - is created from the result, and returned.
+ - is created from the result.
  -
  - When there are transitions recorded locally that have not been done
  - to the remote refs, the transitions are performed in the index,
- - and the existing branch is returned. In this case, the untransitioned
+ - and committed to the existing branch. In this case, the untransitioned
  - remote refs cannot be merged into the branch (since transitions
- - throw away history), so none of them are included in the returned
- - list of refs, and they are added to the list of refs to ignore,
+ - throw away history), so they are added to the list of refs to ignore,
  - to avoid re-merging content from them again.
  -}
-handleTransitions :: Transitions -> [Git.Ref] -> Annex (Maybe (Git.Branch, [Git.Ref]))
+handleTransitions :: Transitions -> [Git.Ref] -> Annex Bool
 handleTransitions localts refs = do
 	m <- M.fromList <$> mapM getreftransition refs
 	let remotets = M.elems m
 	if all (localts ==) remotets
-		then return Nothing
+		then return False
 		else do
 			let allts = combineTransitions (localts:remotets)
 			let (transitionedrefs, untransitionedrefs) =
 				partition (\r -> M.lookup r m == Just allts) refs
-			transitionedbranch <- performTransitions allts (localts /= allts)
+			performTransitions allts (localts /= allts) transitionedrefs
 			ignoreRefs untransitionedrefs
-			return $ Just (transitionedbranch, transitionedrefs)
+			return True
   where
   	getreftransition ref = do
 		ts <- parseTransitionsStrictly "remote" . L.unpack
@@ -444,10 +440,9 @@ getIgnoredRefs = S.fromList . mapMaybe Git.Sha.extractSha . lines <$> content
 		liftIO $ catchDefaultIO "" $ readFile f
 
 {- Performs the specified transitions on the contents of the index file,
- - commits it to the branch, or creates a new branch, and returns 
- - the branch's ref. -}
-performTransitions :: Transitions -> Bool -> Annex Git.Ref
-performTransitions ts neednewbranch = do
+ - commits it to the branch, or creates a new branch. -}
+performTransitions :: Transitions -> Bool -> [Ref] -> Annex ()
+performTransitions ts neednewlocalbranch transitionedrefs = do
 	-- For simplicity & speed, we're going to use the Annex.Queue to
 	-- update the git-annex branch, while it usually holds changes
 	-- for the head branch. Flush any such changes.
@@ -455,18 +450,16 @@ performTransitions ts neednewbranch = do
 	withIndex $ do
 		run $ mapMaybe getTransitionCalculator $ transitionList ts
 		Annex.Queue.flush
-		if neednewbranch
+		if neednewlocalbranch
 			then do
-				committedref <- inRepo $ Git.Branch.commit message fullname []
+				committedref <- inRepo $ Git.Branch.commit message fullname transitionedrefs
 				setIndexSha committedref
-				return committedref
 			else do
 				ref <- getBranch
-				commitBranch ref message [fullname]
-				getBranch
+				commitBranch ref message (nub $ fullname:transitionedrefs)
   where
   	message
-		| neednewbranch = "new branch for transition " ++ tdesc
+		| neednewlocalbranch && null transitionedrefs = "new branch for transition " ++ tdesc
 		| otherwise = "continuing transition " ++ tdesc
 	tdesc = show $ map describeTransition $ transitionList ts
 

Command/Forget.hs

@@ -45,7 +45,7 @@ perform ts True = do
 	recordTransitions Branch.change ts
 	-- get branch committed before contining with the transition
 	Branch.update
-	void $ Branch.performTransitions ts True
+	void $ Branch.performTransitions ts True []
 	next $ return True
 perform _ False = do
 	showLongNote "To forget git-annex branch history, you must specify --force. This deletes metadata!"