Change ProjectUser and GroupProject base class

python-gitlab shouldn't try to provide features that are not existing in
the Gitlab API: GroupProject and ProjectUser objects should not provide
unsupported API methods (no get, no create, no update).

This Closes #346 by making explicit that we don't support these
non-existant methods.

RELEASE_NOTES.rst

@@ -4,6 +4,25 @@ Release notes
 
 This page describes important changes between python-gitlab releases.
 
+Changes from 1.0.2 to 1.1
+=========================
+
+* The ``ProjectUser`` class doesn't inherit from ``User`` anymore, and the
+  ``GroupProject`` class doesn't inherit from ``Project`` anymore. The Gitlab
+  API doesn't provide the same set of features for these objects, so
+  python-gitlab objects shouldn't try to workaround that.
+
+  You can create ``User`` or ``Project`` objects from ``ProjectUser`` and
+  ``GroupProject`` objects using the ``id`` attribute:
+
+  .. code-block:: python
+
+     for gr_project in group.projects.list():
+         # lazy object creation doesn't need an Gitlab API request
+         project = gl.projects.get(gr_project.id, lazy=True)
+         project.default_branch = 'develop'
+         project.save()
+
 Changes from 0.21 to 1.0.0
 ==========================
 

gitlab/v4/objects.py

@@ -1601,7 +1601,7 @@ class ProjectTriggerManager(CRUDMixin, RESTManager):
     _update_attrs = (('description', ), tuple())
 
 
-class ProjectUser(User):
+class ProjectUser(RESTObject):
     pass
 
 
@@ -2244,7 +2244,7 @@ class ProjectManager(CRUDMixin, RESTManager):
                      'with_issues_enabled', 'with_merge_requests_enabled')
 
 
-class GroupProject(Project):
+class GroupProject(RESTObject):
     pass