g = gl.groups.get(group_id)projects = g.projects.list(all=True)for p in projects:    p.default=branch = 'develop'    p.save()

Traceback (most recent call last):  File "./default_branch.py", line 76, in <module>    p.save()  File "/usr/local/lib/python2.7/dist-packages/gitlab/mixins.py", line 275, in save    updated_data = self._get_updated_data()  File "/usr/local/lib/python2.7/dist-packages/gitlab/mixins.py", line 254, in _get_updated_data    required, optional = self.manager.get_update_attrs()AttributeError: 'GroupProjectManager' object has no attribute 'get_update_attrs'