sync --quiet

* sync: When --quiet is used, run git commit, push, and pull without
  their ususual output.
* merge: When --quiet is used, run git merge without its usual output.

This might also make --quiet work better for some other commands
that make commits, like git-annex adjust.

Sponsored-by: Kevin Mueller on Patreon

Assistant/Threads/Merger.hs

@@ -90,8 +90,10 @@ onChange file
 					]
 				void $ liftAnnex $ do
 					cmode <- annexCommitMode <$> Annex.getGitConfig
+					mc <- Command.Sync.mergeConfig
 					Command.Sync.merge
-						currbranch Command.Sync.mergeConfig
+						currbranch
+						mc
 						def
 						cmode
 						changedbranch