Description of problem:
anaconda 19.13 exception report
Traceback (most recent call first):
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/user.py", line 114, in run
    self._user.gid = int(self.builder.get_widget("gid").get_value())
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/user.py", line 422, in on_advanced_clicked
    response = self._advanced.run()
AttributeError: 'Builder' object has no attribute 'get_widget'

Version-Release number of selected component (if applicable):
F19-Alpha-TC2
anaconda-19.13

How reproducible:
always

Steps to Reproduce:
1. start graphical installation
2. configure partitioning/packages
3. begin with the installation
4. go to the User Creation spoke
5. click on the "Advanced..." button
6. check "Specify a group ID manually:"
7. click "Save Changes"
  
Actual results:
traceback

Expected results:
no traceback

Additional info:
This cannot be reproduced if I try the same steps, but check "Specify a user ID manually:"