assistant: Deal with upcoming git's refusal to merge unrelated histories by default

git 2.8.1 (or perhaps 2.9.0) is going to prevent git merge from merging in
unrelated branches. Since the webapp's pairing etc features often combine
together repositories with unrelated histories, work around this behavior
change by setting GIT_MERGE_ALLOW_UNRELATED_HISTORIES when the assistant
merges.

Note though that this is not done for git annex sync's merges, so
it will follow git's default or configured behavior.

3 files changed, 16 insertions, 17 deletions

diff --git a/Annex/AdjustedBranch.hs b/Annex/AdjustedBranch.hs
index 26a24d8e6..2b014a12a 100644
--- a/Annex/AdjustedBranch.hs
+++ b/Annex/AdjustedBranch.hs
@@ -260,8 +260,8 @@ adjustedBranchCommitMessage = "git-annex adjusted branch"
 {- Update the currently checked out adjusted branch, merging the provided
  - branch into it. Note that the provided branch should be a non-adjusted
  - branch. -}
-updateAdjustedBranch :: Branch -> (OrigBranch, Adjustment) -> Git.Branch.CommitMode -> Annex Bool
-updateAdjustedBranch tomerge (origbranch, adj) commitmode = catchBoolIO $
+updateAdjustedBranch :: Branch -> (OrigBranch, Adjustment) -> [Git.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
+updateAdjustedBranch tomerge (origbranch, adj) mergeconfig commitmode = catchBoolIO $
 	join $ preventCommits go
   where
 	adjbranch@(AdjBranch currbranch) = originalToAdjusted origbranch adj
@@ -304,7 +304,7 @@ updateAdjustedBranch tomerge (origbranch, adj) commitmode = catchBoolIO $
 				showAction $ "Merging into " ++ fromRef (Git.Ref.base origbranch)
 				-- The --no-ff is important; it makes git
 				-- merge not care that the work tree is empty.
-				merged <- inRepo (Git.Merge.mergeNonInteractive' [Param "--no-ff"] tomerge commitmode)
+				merged <- inRepo (Git.Merge.merge' [Param "--no-ff"] tomerge mergeconfig commitmode)
 					<||> (resolveMerge (Just updatedorig) tomerge True <&&> commitResolvedMerge commitmode)
 				if merged
 					then do
@@ -340,7 +340,7 @@ updateAdjustedBranch tomerge (origbranch, adj) commitmode = catchBoolIO $
 		-- this commit will be a fast-forward.
 		adjmergecommitff <- commitAdjustedTree' adjtree (BasisBranch mergecommit) [currbranch]
 		showAction "Merging into adjusted branch"
-		ifM (autoMergeFrom adjmergecommitff (Just currbranch) commitmode)
+		ifM (autoMergeFrom adjmergecommitff (Just currbranch) mergeconfig commitmode)
 			( reparent adjtree adjmergecommit =<< getcurrentcommit
 			, return False
 			)
diff --git a/Annex/AutoMerge.hs b/Annex/AutoMerge.hs
index e6f2be552..26f58a98e 100644
--- a/Annex/AutoMerge.hs
+++ b/Annex/AutoMerge.hs
@@ -43,16 +43,16 @@ import qualified Data.ByteString.Lazy as L
  - Callers should use Git.Branch.changed first, to make sure that
  - there are changes from the current branch to the branch being merged in.
  -}
-autoMergeFrom :: Git.Ref -> Maybe Git.Ref -> Git.Branch.CommitMode -> Annex Bool
-autoMergeFrom branch currbranch commitmode = do
+autoMergeFrom :: Git.Ref -> Maybe Git.Ref -> [Git.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
+autoMergeFrom branch currbranch mergeconfig commitmode = do
 	showOutput
 	case currbranch of
 		Nothing -> go Nothing
 		Just b -> go =<< inRepo (Git.Ref.sha b)
   where
 	go old = ifM isDirect
-		( mergeDirect currbranch old branch (resolveMerge old branch False) commitmode
-		, inRepo (Git.Merge.mergeNonInteractive branch commitmode)
+		( mergeDirect currbranch old branch (resolveMerge old branch False) mergeconfig commitmode
+		, inRepo (Git.Merge.merge branch mergeconfig commitmode)
 			<||> (resolveMerge old branch False <&&> commitResolvedMerge commitmode)
 		)
 
diff --git a/Annex/Direct.hs b/Annex/Direct.hs
index 782803e71..5724d1162 100644
--- a/Annex/Direct.hs
+++ b/Annex/Direct.hs
@@ -162,8 +162,8 @@ addDirect file cache = do
  - file. This is the same as what git does when updating the index
  - normally.
  -}
-mergeDirect :: Maybe Git.Ref -> Maybe Git.Ref -> Git.Branch -> Annex Bool -> Git.Branch.CommitMode -> Annex Bool
-mergeDirect startbranch oldref branch resolvemerge commitmode = exclusively $ do
+mergeDirect :: Maybe Git.Ref -> Maybe Git.Ref -> Git.Branch -> Annex Bool -> [Git.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
+mergeDirect startbranch oldref branch resolvemerge mergeconfig commitmode = exclusively $ do
 	reali <- liftIO . absPath =<< fromRepo indexFile
 	tmpi <- liftIO . absPath =<< fromRepo indexFileLock
 	liftIO $ whenM (doesFileExist reali) $
@@ -176,7 +176,7 @@ mergeDirect startbranch oldref branch resolvemerge commitmode = exclusively $ do
 		createDirectoryIfMissing True d
 
 	withIndexFile tmpi $ do
-		merged <- stageMerge d branch commitmode
+		merged <- stageMerge d branch mergeconfig commitmode
 		ok <- if merged
 			then return True
 			else resolvemerge
@@ -195,19 +195,18 @@ mergeDirect startbranch oldref branch resolvemerge commitmode = exclusively $ do
 
 {- Stage a merge into the index, avoiding changing HEAD or the current
  - branch. -}
-stageMerge :: FilePath -> Git.Branch -> Git.Branch.CommitMode -> Annex Bool
-stageMerge d branch commitmode = do
+stageMerge :: FilePath -> Git.Branch -> [Git.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
+stageMerge d branch mergeconfig commitmode = do
 	-- XXX A bug in git makes stageMerge unsafe to use if the git repo
 	-- is configured with core.symlinks=false
-	-- Using mergeNonInteractive is not ideal though, since it will
+	-- Using merge is not ideal though, since it will
 	-- update the current branch immediately, before the work tree
 	-- has been updated, which would leave things in an inconsistent
 	-- state if mergeDirectCleanup is interrupted.
 	-- <http://marc.info/?l=git&m=140262402204212&w=2>
-	liftIO $ print ("stagemerge in", d)
 	merger <- ifM (coreSymlinks <$> Annex.getGitConfig)
-		( return Git.Merge.stageMerge
-		, return $ \ref -> Git.Merge.mergeNonInteractive ref commitmode
+		( return $ \ref -> Git.Merge.stageMerge ref mergeconfig
+		, return $ \ref -> Git.Merge.merge ref mergeconfig commitmode
 		)
 	inRepo $ \g -> do
 		wd <- liftIO $ absPath d