Removing @Exported from getRepositories() since it does not work anyway.
RemoteConfig, being in JGit, is not an @ExportedBean.
Stapler throws NotExportableException, but Property.writeValue ignores it since it is part of a list.
Thus regardless of how the SCM is configured, you always get the useless
    "repositories" : [
      {
        
      }
    ],
Pointless for GitSCM.getBranches() to be @Exported unless BranchSpec is an @ExportedBean!
[FIXED JENKINS-9843] PreBuildMergeOptions.getMergeRemote() cannot be @Exported, since the return type is not @ExportedBean.
Corrects attempted fix b3ddce6.
[JENKINS-9843] Forgot to record what problem this was fixing.