handle case of adding populated drive to just created repo

The just created repo has no master branch commits yet. This is now
handled, merging in the master branch from the populated drive.

Command/Sync.hs

@@ -123,7 +123,7 @@ pullRemote remote branch = do
 	next $ do
 		showOutput
 		stopUnless fetch $
-			next $ mergeRemote remote branch
+			next $ mergeRemote remote (Just branch)
 	where
 		fetch = inRepo $ Git.Command.runBool "fetch"
 			[Param $ Remote.name remote]
@@ -132,11 +132,17 @@ pullRemote remote branch = do
  - Which to merge from? Well, the master has whatever latest changes
  - were committed, while the synced/master may have changes that some
  - other remote synced to this remote. So, merge them both. -}
-mergeRemote :: Remote -> Git.Ref -> CommandCleanup
-mergeRemote remote branch = all id <$> (mapM merge =<< tomerge)
+mergeRemote :: Remote -> (Maybe Git.Ref) -> CommandCleanup
+mergeRemote remote b = case b of
+	Nothing -> do
+		branch <- inRepo Git.Branch.currentUnsafe
+		all id <$> (mapM merge $ branchlist branch)
+	Just _ -> all id <$> (mapM merge =<< tomerge (branchlist b))
 	where
 		merge = mergeFrom . remoteBranch remote
-		tomerge = filterM (changed remote) [branch, syncBranch branch]
+		tomerge branches = filterM (changed remote) branches
+		branchlist Nothing = []
+		branchlist (Just branch) = [branch, syncBranch branch]
 
 pushRemote :: Remote -> Git.Ref -> CommandStart
 pushRemote remote branch = go =<< needpush