This error shouldn't normally occur, but we ran into it once and it'd better for Allura to be forgiving in its input.
File '/var/local/allura/Allura/allura/model/project.py', line 877 in admins
return self.users_with_role('Admin')
File '/var/local/allura/Allura/allura/model/project.py', line 871 in users_with_role
for user in g.credentials.users_with_named_role(self.root_project._id, role_name):
File '/var/local/allura/Allura/allura/lib/security.py', line 150 in users_with_named_role
role = RoleCache(self, [r for r in self.project_roles(project_id) if r['name'] == name])
KeyError: 'name'