use ZODB4 branch

sources.cfg

@@ -18,7 +18,7 @@ MultiMapping = git ${remotes:github}/MultiMapping pushurl=${remotes:github_push}
 nt_svcutils = git ${remotes:github}/nt_svcutils pushurl=${remotes:github_push}/nt_svcutils
 Persistence = git ${remotes:github}/Persistence pushurl=${remotes:github_push}/Persistence
 Products.OFSP = git ${remotes:github}/Products.OFSP pushurl=${remotes:github_push}/Products.OFSP
-Products.ZCatalog = git ${remotes:github}/Products.ZCatalog pushurl=${remotes:github_push}/Products.ZCatalog
+Products.ZCatalog = git ${remotes:github}/Products.ZCatalog pushurl=${remotes:github_push}/Products.ZCatalog branch=tomgross-zodbdep
 Products.ZCTextIndex = git ${remotes:github}/Products.ZCTextIndex pushurl=${remotes:github_push}/Products.ZCTextIndex
 Record = git ${remotes:github}/Record pushurl=${remotes:github_push}/Record
 tempstorage = git ${remotes:github}/tempstorage pushurl=${remotes:github_push}/tempstorage