ensure that git-annex branch is pushed after a successful transfer

I now have this topology working:

   assistant ---> {bare repo, special remote} <--- assistant

And, I think, also this one:

        +----------- bare repo --------+
        v                              v
  assistant ---> special remote <--- assistant

While before with assistant <---> assistant connections, both sides got
location info updated after a transfer, in this topology, the bare repo
*might* get its location info updated, but the other assistant has no way to
know that it did. And a special remote doesn't record location info,
so transfers to it won't propigate out location log changes at all.

So, for these to work, after a transfer succeeds, the git-annex branch
needs to be pushed. This is done by recording a synthetic commit has
occurred, which lets the pusher handle pushing out the change (which will
include actually committing any still journalled changes to the git-annex
branch).

Of course, this means rather a lot more syncing action than happened
before. At least the pusher bundles together very close together pushes,
somewhat. Currently it just waits 2 seconds between each push.

Assistant/Commits.hs

@@ -9,12 +9,9 @@ module Assistant.Commits where
 
 import Utility.TSet
 
-import Data.Time.Clock
-
 type CommitChan = TSet Commit
 
-data Commit = Commit UTCTime
-	deriving (Show)
+data Commit = Commit
 
 newCommitChan :: IO CommitChan
 newCommitChan = newTSet
@@ -30,5 +27,5 @@ refillCommits :: CommitChan -> [Commit] -> IO ()
 refillCommits = putTSet
 
 {- Records a commit in the channel. -}
-recordCommit :: CommitChan -> Commit -> IO ()
-recordCommit = putTSet1
+recordCommit :: CommitChan -> IO ()
+recordCommit = flip putTSet1 Commit