Governor Jerry Brown, with a stroke of his pen has solved a problem that never existed. Open carry in California is now unlawful. It was in fact rather limited anyway - while it didn't require an existing concealed carry permit, it was only lawful if it the firearm was unloaded. There was nothing preventing an OCer from keeping ammunition close at hand, but having it inside the weapon was a no-no.
Hopefully the Second Amendment Foundation will go after this one vigorously, since California is notoriously arbitrary with issuance of concealed carry permits.