sync: fix missing import for -q

Some refactors during review dropped this import when it was reworked,
but it's still needed when using the --quiet setting.

Change-Id: I6d9302ef5a056e52415ea63f35bad592b9dfa75d
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/303942
Reviewed-by: Raman Tenneti <rtenneti@google.com>
Tested-by: Mike Frysinger <vapier@google.com>
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 21bc5e7..aafec1d 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -51,7 +51,7 @@
 import gitc_utils
 from project import Project
 from project import RemoteSpec
-from command import Command, MirrorSafeCommand
+from command import Command, MirrorSafeCommand, WORKER_BATCH_SIZE
 from error import RepoChangedException, GitError, ManifestParseError
 import platform_utils
 from project import SyncBuffer