configuration to disable automatic merge conflict resolution

* Added annex.resolvemerge configuration, which can be set to false to
  disable the usual automatic merge conflict resolution done by git-annex
  sync and the assistant.
* sync: Added --no-resolvemerge option.

Note that disabling merge conflict resolution is probably not a good idea
in a direct mode repo or adjusted branch. Since updates to both are done
outside the usual work tree, if it fails the tree is not left in a
conflicted state, and it would be hard to manually resolve the conflict.
Still, made annex.resolvemerge be supported in those cases for consistency.

This commit was sponsored by Riku Voipio.

2 files changed, 12 insertions, 7 deletions

diff --git a/Annex/AdjustedBranch.hs b/Annex/AdjustedBranch.hs
index c0225540a..52f73e638 100644
--- a/Annex/AdjustedBranch.hs
+++ b/Annex/AdjustedBranch.hs
@@ -318,8 +318,8 @@ findAdjustingCommit (AdjBranch b) = go =<< catCommit b
 {- 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.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
-updateAdjustedBranch tomerge (origbranch, adj) mergeconfig commitmode = catchBoolIO $
+updateAdjustedBranch :: Branch -> (OrigBranch, Adjustment) -> [Git.Merge.MergeConfig] -> Annex Bool -> Git.Branch.CommitMode -> Annex Bool
+updateAdjustedBranch tomerge (origbranch, adj) mergeconfig canresolvemerge commitmode = catchBoolIO $
 	join $ preventCommits go
   where
 	adjbranch@(AdjBranch currbranch) = originalToAdjusted origbranch adj
@@ -417,7 +417,7 @@ updateAdjustedBranch tomerge (origbranch, adj) mergeconfig commitmode = catchBoo
 		-- this commit will be a fast-forward.
 		adjmergecommitff <- commitAdjustedTree' adjtree (BasisBranch mergecommit) [currbranch]
 		showAction "Merging into adjusted branch"
-		ifM (autoMergeFrom adjmergecommitff (Just currbranch) mergeconfig commitmode)
+		ifM (autoMergeFrom adjmergecommitff (Just currbranch) mergeconfig canresolvemerge commitmode)
 			( reparent adjtree adjmergecommit =<< getcurrentcommit
 			, return False
 			)
diff --git a/Annex/AutoMerge.hs b/Annex/AutoMerge.hs
index 7f982e515..91f8fc99e 100644
--- a/Annex/AutoMerge.hs
+++ b/Annex/AutoMerge.hs
@@ -43,18 +43,18 @@ 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.Merge.MergeConfig] -> Git.Branch.CommitMode -> Annex Bool
-autoMergeFrom branch currbranch mergeconfig commitmode = do
+autoMergeFrom :: Git.Ref -> Maybe Git.Ref -> [Git.Merge.MergeConfig] -> Annex Bool -> Git.Branch.CommitMode -> Annex Bool
+autoMergeFrom branch currbranch mergeconfig canresolvemerge 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) mergeconfig commitmode
+		( mergeDirect currbranch old branch resolvemerge mergeconfig commitmode
 		, do
 			r <- inRepo (Git.Merge.merge branch mergeconfig commitmode)
-				<||> (resolveMerge old branch False <&&> commitResolvedMerge commitmode)
+				<||> (resolvemerge <&&> commitResolvedMerge commitmode)
 			-- Merging can cause new associated files to appear
 			-- and the smudge filter will add them to the database.
 			-- To ensure that this process sees those changes,
@@ -62,6 +62,11 @@ autoMergeFrom branch currbranch mergeconfig commitmode = do
 			Database.Keys.closeDb
 			return r
 		)
+	  where
+		resolvemerge = ifM canresolvemerge
+			( resolveMerge old branch False
+			, return False 
+			)
 
 {- Resolves a conflicted merge. It's important that any conflicts be
  - resolved in a way that itself avoids later merge conflicts, since