Description of problem:
When I call client.group_members("packager") it results in traceback (see below)

Version-Release number of selected component (if applicable):
python3-fedora-0.7.1-1.fc23.noarch

How reproducible:
deterministc

Steps to Reproduce:
#!/usr/bin/python3
from fedora.client import AuthError, AccountSystem
client = AccountSystem()
#client.username = "msuchy"
#client.password = "XXXX"
packagers = client.group_members("packager")

Actual results:
$ ./guard-fedora-sponsors.py
Traceback (most recent call last):
  File "./guard-fedora-sponsors.py", line 97, in <module>
    packagers = client.group_members("packager")
  File "/usr/lib/python3.4/site-packages/fedora/client/fas2.py", line 395, in group_members
    quote(groupname), auth=True)
  File "/usr/lib/python3.4/site-packages/fedora/client/baseclient.py", line 362, in send_request
    for key, value in auth_params.items() if not value]
  File "/usr/lib/python3.4/site-packages/fedora/client/baseclient.py", line 361, in <listcomp>
    [auth_params.__delitem__(key)
RuntimeError: dictionary changed size during iteration