make sync aware of adjusted branches

So, it will pull and push the original branch, not the adjusted one.

And, for merging, it will use updateAdjustedBranch (not implemented yet).

Note that remaining uses of Git.Branch.current need to be checked too;
for things that should act on the original branch, and not the adjusted
branch.

Annex/AdjustedBranch.hs

@@ -67,9 +67,6 @@ adjustedToOriginal b
 	bs = fromRef b
 	prefixlen = length adjustedBranchPrefix
 
-getAdjustment :: Annex (Maybe (Adjustment, OrigBranch))
-getAdjustment = maybe Nothing adjustedToOriginal <$> inRepo Git.Branch.current
-
 originalBranch :: Annex (Maybe OrigBranch)
 originalBranch = fmap getorig <$> inRepo Git.Branch.current
   where
@@ -123,6 +120,6 @@ commitAdjustedTree treesha parent = go =<< catCommit parent
 
 {- Update the currently checked out adjusted branch, merging the provided
  - branch into it. -}
-updateAdjustedBranch :: Adjustment -> OrigBranch -> Branch -> Annex ()
+updateAdjustedBranch :: Adjustment -> OrigBranch -> Branch -> Annex Bool
 updateAdjustedBranch mergebranch = do
 	error "updateAdjustedBranch"