Bulk Jenkins git repo configuration through Groovy interface.

gistfile1.groovy

// Loop through Jenkins projects, adding a git repo for any project without a repo defined.
def projects = hudson.model.Hudson.instance;
projects.getItems(hudson.model.Project).each {
    proj -> 
      if (proj.getScm().type == "hudson.scm.NullSCM")  {
       proj.scm = new hudson.plugins.git.GitSCM("git://path/to/your/repo.git");
       println("Project: " + proj.displayName + " SCM: " + proj.getScm().type);
      }
}

// Same as above, but added logic to only update builds where the name contains 'FOO'
def projects = hudson.model.Hudson.instance
projects.getItems(hudson.model.Project).each {
    proj -> 
      if (proj.getScm().type == "hudson.scm.NullSCM" && proj.displayName.contains('FOO'))  {
       proj.scm = new hudson.plugins.git.GitSCM("git://path/to/your/repo.git");
       println("Project: " + proj.displayName + " SCM: " + proj.getScm().type);
      }
 
}