git-remote-annex: mostly implemented pushing

Full pushing will probably work, but is untested.
Incremental pushing is not implemented yet.

While a fairly straightforward port of the shell prototype, the details
of exactly how to get the objects to the remote were tricky. And the
prototype did not consider how to deal with partial failures and
interruptions.

I've taken considerable care to make sure it always leaves things in a
consistent state when interrupted or when it loses access to a remote in
the middle of a push.

Sponsored-by: Leon Schuermann on Patreon

Git/Bundle.hs

@@ -23,3 +23,16 @@ listHeads bundle repo = map gen . S8.lines <$>
 
 unbundle :: FilePath -> Repo -> IO ()
 unbundle bundle = runQuiet [Param "bundle", Param "unbundle", File bundle]
+
+create :: FilePath -> [Ref] -> Repo -> IO ()
+create bundle refs repo = pipeWrite
+	[ Param "bundle"
+	, Param "create"
+	, Param "--quiet"
+	, File bundle
+	, Param "--stdin"
+	] repo writerefs
+  where
+	writerefs h = do
+		mapM_ (S8.hPutStrLn h . fromRef') refs
+		hClose h