This change fixes PUSH permission check for blocking draft changes:
[access "refs/drafts/*"]
push = block group Anonymous Users
MagicBranchInput.parse() method updates the ref name, converting
the refs/drafts/master to refs/heads/master. All checks happens
with refs/heads/master. Only draft flag is set to true to mark the
change as draft. Use this flag and explicitly call
controlForRef("refs/drafts/refs/heads/master")
to check PUSH permission is not blocked for the ref.
Change-Id: I236a2969cf16e39198c26ebe1628de5313b660bd
07ddca593b