Use AccessControl branch 2.13 again.

The PR was merged, but we still need a checkout at this moment.

sources.cfg

@@ -3,7 +3,7 @@ github = git://github.com/zopefoundation
 github_push = git@github.com:zopefoundation
 
 [sources]
-AccessControl = git ${remotes:github}/AccessControl pushurl=${remotes:github_push}/AccessControl branch=plone-hotfix20171128-format-213
+AccessControl = git ${remotes:github}/AccessControl pushurl=${remotes:github_push}/AccessControl branch=2.13
 Acquisition = git ${remotes:github}/Acquisition pushurl=${remotes:github_push}/Acquisition branch=2.13
 DateTime = git ${remotes:github}/DateTime pushurl=${remotes:github_push}/DateTime branch=2.12
 DocumentTemplate = git ${remotes:github}/DocumentTemplate pushurl=${remotes:github_push}/DocumentTemplate branch=2.13