src/Tasks.php
public function pullConfig() {
    $project_properties = $this->getProjectProperties();
    $terminus_site_env  = $this->getPantheonSiteEnv($this->databaseSourceOfTruth());

    $grab_database = $this->confirm("To pull the latest config, you should create a new backup on Pantheon. Create backup now?");
    if ($grab_database == 'y') {
      $terminus_url_request = $this->taskExec('terminus backup:create ' . $terminus_site_env . ' --element="db"')
        ->dir($project_properties['web_root'])
        ->interactive(false)
        ->run();

      if (!$terminus_url_request->wasSuccessful()) {
        $this->yell('Could not make a Database backup of "'. $terminus_site_env . '"! See if you can make one manually.');
        return FALSE;
      }
    }

    $do_composer_install = $this->downloadPantheonBackup($this->databaseSourceOfTruth());

    if ($do_composer_install && $this->importLocal()) {
      $this->taskComposerInstall()
        ->optimizeAutoloader()
        ->run();
      $drush_commands = [
        'drush_clear_cache_again' => 'drush cr',
        'drush_grab_config_changes' => 'drush config-export -y',
      ];
      $this->taskExec(implode(' && ', $drush_commands))
        ->dir($project_properties['web_root'])
        ->run();

      // Ignore config-local changes -- the $database_of_truth site doesn't know about them.
      $this->taskGitStack()
        ->stopOnFail()
        ->checkout('config-local')
        ->run();

      $this->yell('"'. $this->databaseSourceOfTruth() . '" site config exported to your local. Commit this branch and make a PR against master. Don\'t forget to `robo install` again before resuming development!');
    }
  }
public function pullConfig() {
    $project_properties = $this->getProjectProperties();
    $terminus_site_env  = $this->getPantheonSiteEnv($this->databaseSourceOfTruth());

    $grab_database = $this->confirm("To pull the latest config, you should create a new backup on Pantheon. Create backup now?");
    if ($grab_database == 'y') {
      $terminus_url_request = $this->taskExec('terminus backup:create ' . $terminus_site_env . ' --element="db"')
        ->dir($project_properties['web_root'])
        ->interactive(false)
        ->run();

      if (!$terminus_url_request->wasSuccessful()) {
        $this->yell('Could not make a Database backup of "'. $terminus_site_env . '"! See if you can make one manually.');
        return FALSE;
      }
    }

    $do_composer_install = $this->downloadPantheonBackup($this->databaseSourceOfTruth());

    if ($do_composer_install && $this->importLocal()) {
      $this->taskComposerInstall()
        ->optimizeAutoloader()
        ->run();
      $drush_commands = [
        'drush_clear_cache_again' => 'drush cr',
        'drush_grab_config_changes' => 'drush config-export -y',
      ];
      $this->taskExec(implode(' && ', $drush_commands))
        ->dir($project_properties['web_root'])
        ->run();

      // Ignore config-local changes -- the $database_of_truth site doesn't know about them.
      $this->taskGitStack()
        ->stopOnFail()
        ->checkout('config-local')
        ->run();

      $this->yell('"'. $this->databaseSourceOfTruth() . '" site config exported to your local. Commit this branch and make a PR against master. Don\'t forget to `robo install` again before resuming development!');
    }
  }
public function pullConfig ( ) { $ project_properties = $ this -> getProjectProperties ( ) ; $ terminus_site_env = $ this -> getPantheonSiteEnv ( $ this -> databaseSourceOfTruth ( ) ) ; $ grab_database = $ this -> confirm ( "To pull the latest config, you should create a new backup on Pantheon. Create backup now?" ) ; if ( $ grab_database == 'y' ) { $ terminus_url_request = $ this -> taskExec ( 'terminus backup:create ' . $ terminus_site_env . ' --element="db"' ) -> dir ( $ project_properties [ 'web_root' ] ) -> interactive ( false ) -> run ( ) ; if ( ! $ terminus_url_request -> wasSuccessful ( ) ) { $ this -> yell ( 'Could not make a Database backup of "' . $ terminus_site_env . '"! See if you can make one manually.' ) ; return FALSE ; } } $ do_composer_install = $ this -> downloadPantheonBackup ( $ this -> databaseSourceOfTruth ( ) ) ; if ( $ do_composer_install && $ this -> importLocal ( ) ) { $ this -> taskComposerInstall ( ) -> optimizeAutoloader ( ) -> run ( ) ; $ drush_commands = [ 'drush_clear_cache_again' => 'drush cr' , 'drush_grab_config_changes' => 'drush config-export -y' , ] ; $ this -> taskExec ( implode ( ' && ' , $ drush_commands ) ) -> dir ( $ project_properties [ 'web_root' ] ) -> run ( ) ; // Ignore config-local changes -- the $database_of_truth site doesn't know about them. $ this -> taskGitStack ( ) -> stopOnFail ( ) -> checkout ( 'config-local' ) -> run ( ) ; $ this -> yell ( '"' . $ this -> databaseSourceOfTruth ( ) . '" site config exported to your local. Commit this branch and make a PR against master. Don\'t forget to `robo install` again before resuming development!' ) ; } }
Pull the config from the live site down to your local.

Run this command from a branch based off the last release tag on github.
For example:
git checkout my_last_release
git checkout -b this_release_date
robo pull:config
git commit .
git push

Afterwards, make a PR against master for these changes and merge them.
Do this BEFORE merging develop into master.
Pull the config from the live site down to your local .