assistant: Fix bug, introduced in last release, that caused the assistant to make many unncessary empty merge commits.

Annex/AutoMerge.hs

@@ -28,7 +28,11 @@ import qualified Data.Set as S
 
 {- Merges from a branch into the current branch
  - (which may not exist yet),
- - with automatic merge conflict resolution. -}
+ - with automatic merge conflict resolution.
+ -
+ - Callers should use Git.Branch.changed first, to make sure that
+ - there are changed 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
 	showOutput

Assistant/Threads/Merger.hs

@@ -79,11 +79,13 @@ onChange file
 
 	mergecurrent (Just current)
 		| equivBranches changedbranch current = do
-			debug
-				[ "merging", Git.fromRef changedbranch
-				, "into", Git.fromRef current
-				]
-			void $ liftAnnex  $ autoMergeFrom changedbranch (Just current) Git.Branch.AutomaticCommit
+			void $ liftAnnex $ autoMergeFrom changedbranch (Just current) Git.Branch.AutomaticCommit 
+			whenM (liftAnnex $ inRepo $ Git.Branch.changed current changedbranch) $ do
+				debug
+					[ "merging", Git.fromRef changedbranch
+					, "into", Git.fromRef current
+					]
+				void $ liftAnnex $ autoMergeFrom changedbranch (Just current) Git.Branch.AutomaticCommit
 	mergecurrent _ = noop
 
 	handleDesynced = case fromTaggedBranch changedbranch of

debian/changelog

@@ -18,6 +18,8 @@ git-annex (5.20140614) UNRELEASED; urgency=medium
     for git-annex branch commits and commits made by the assistant.
   * Fix memory leak when committing millions of changes to the git-annex
     branch, eg after git-annex add has run on 2 million files in one go.
+  * assistant: Fix bug, introduced in last release, that caused the assistant
+    to make many unncessary empty merge commits.
 
  -- Joey Hess <joeyh@debian.org>  Mon, 16 Jun 2014 11:28:42 -0400
 

doc/bugs/Assistant_merge_loop.mdwn

@@ -14,3 +14,5 @@ Using the standalone build, 64bit, on ArchLinux, Fedora 20 and Ubuntu 14.04.
     local repository version: 5
     supported repository version: 5
     upgrade supported from repository versions: 0 1 2 4
+
+> [[fixed|done]] --[[Joey]]