support old versions of git that do not have --allow-empty-message

Assistant/Threads/Committer.hs

@@ -20,6 +20,7 @@ import qualified Annex
 import qualified Annex.Queue
 import qualified Git.Command
 import qualified Git.HashObject
+import qualified Git.Version
 import Git.Types
 import qualified Command.Add
 import Utility.ThreadScheduler
@@ -74,19 +75,23 @@ commitThread st changechan commitchan transferqueue dstatus = thread $ runEvery
 commitStaged :: Annex Bool
 commitStaged = do
 	Annex.Queue.flush
-	void $ inRepo $ Git.Command.runBool "commit"
-		[ Param "--allow-empty-message"
-		, Param "-m", Param ""
-		-- Avoid running the usual git-annex pre-commit hook;
-		-- watch does the same symlink fixing, and we don't want
-		-- to deal with unlocked files in these commits.
+	void $ inRepo $ Git.Command.runBool "commit" $ nomessage
+		[ Param "--quiet"
+		{- Avoid running the usual git-annex pre-commit hook;
+		 - watch does the same symlink fixing, and we don't want
+		 - to deal with unlocked files in these commits. -}
 		, Param "--no-verify"
-		, Param "--quiet"
 		]
 	{- Empty commits may be made if tree changes cancel
 	 - each other out, etc. Git returns nonzero on those, so
 	 - don't propigate out commit failures. -}
 	return True
+	where
+		nomessage ps
+			| Git.Version.older "1.7.2" = Param "-m"
+				: Param "autocommit" : ps
+			| otherwise = Param "--allow-empty-message" 
+				: Param "-m" : Param "" : ps
 
 {- Decide if now is a good time to make a commit.
  - Note that the list of change times has an undefined order.