Description of problem:
Tried to put root partition on iSCSI disk in blivet-gui. Selected iSCSI device, added new partition, put "/" as mountpoint, clicked on "OK".

Version-Release number of selected component:
anaconda-26.21.6-1

The following was filed automatically by anaconda:
anaconda 26.21.6-1 exception report
Traceback (most recent call first):
  File "/usr/lib/python3.6/site-packages/blivetgui/blivet_utils.py", line 1134, in add_device
    add_function = self.add_dict[user_input.device_type]
  File "/usr/lib/python3.6/site-packages/blivetgui/osinstall.py", line 78, in remote_call
    return utils_method(*args)
  File "/usr/lib/python3.6/site-packages/blivetgui/blivetgui.py", line 442, in add_device
    result = self.client.remote_call("add_device", user_input)
KeyError: None

Additional info:
addons:         com_redhat_docker, com_redhat_kdump
cmdline:        /usr/libexec/system-python  /sbin/anaconda
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         4.11.0-2.fc26.x86_64
product:        Fedora
release:        Cannot get release name.
type:           anaconda
version:        26