"oaconfig install" fails with "ValueError: IPAddress() does not support netmasks or subnet prefixes!"

    Reading file /etc/sysconfig/openattic
    Creating tables ...
    Creating table auth_permission
    Creating table auth_group_permissions
    Creating table auth_group
    Creating table auth_user_groups
    Creating table auth_user_user_permissions
    Creating table auth_user
    Creating table django_content_type
    Creating table django_session
    Creating table django_site
    Creating table django_admin_log
    Creating table authtoken_token
    Creating table ifconfig_host
    Creating table ifconfig_hostgroup_hosts
    Creating table ifconfig_hostgroup
    Creating table ifconfig_netdevice_brports
    Creating table ifconfig_netdevice_slaves
    Creating table ifconfig_netdevice
    Creating table ifconfig_ipaddress
    Creating table userprefs_userprofile
    Creating table userprefs_userpreference
    Creating table cmdlog_logentry
    Creating table nagios_command
    Creating table nagios_graph
    Creating table nagios_service
    Creating table ceph_cephcluster
    Creating table ceph_cephpool
    Creating table ceph_cepherasurecodeprofile
    Creating table ceph_cephosd
    Creating table ceph_cephpg
    Creating table ceph_cephrbd
    Creating table ceph_cephfs
    Creating table ceph_crushmapversion
    Creating table ceph_iscsi_iscsiinterface
    Creating table ceph_iscsi_iscsitarget
    Creating table ceph_nfs_ganeshaexport
    Creating table taskqueue_taskqueue
    Installing custom SQL ...
    Installing indexes ...
    Installed 8 object(s) from 1 fixture(s)
    Reading file /etc/sysconfig/openattic
    Created default user "openattic" with password "openattic".
    Adding lo
    Adding  {'peer': u'127.0.0.1', 'netmask': u'255.0.0.0', 'addr': u'127.0.0.1'}
    Traceback (most recent call last):
      File "manage.py", line 25, in <module>
        execute_from_command_line(sys.argv)
      File "/usr/lib/python2.7/site-packages/django/core/management/__init__.py", line 399, in execute_from_command_line
        utility.execute()
      File "/usr/lib/python2.7/site-packages/django/core/management/__init__.py", line 392, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 242, in run_from_argv
        self.execute(*args, **options.__dict__)
      File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 285, in execute
        output = self.handle(*args, **options)
      File "/usr/share/openattic/sysutils/management/commands/install.py", line 126, in handle
        self.post_install(**options)
      File "/usr/share/openattic/sysutils/management/commands/install.py", line 118, in post_install
        call_command('post_install')
      File "/usr/lib/python2.7/site-packages/django/core/management/__init__.py", line 159, in call_command
        return klass.execute(*args, **defaults)
      File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 285, in execute
        output = self.handle(*args, **options)
      File "/usr/share/openattic/sysutils/management/commands/post_install.py", line 48, in handle
        sysutils.models.post_install.send(sender=sysutils.models)
      File "/usr/lib/python2.7/site-packages/django/dispatch/dispatcher.py", line 185, in send
        response = receiver(signal=self, sender=sender, **named)
      File "/usr/share/openattic/ifconfig/management/__init__.py", line 127, in create_interfaces
        ipnet = netaddr.IPNetwork(addr["addr"] + "/" + addr["netmask"])
      File "/usr/lib/python2.7/site-packages/netaddr/ip/__init__.py", line 928, in __init__
        implicit_prefix, flags)
      File "/usr/lib/python2.7/site-packages/netaddr/ip/__init__.py", line 805, in parse_ip_network
        mask = IPAddress(val2, module.version, flags=INET_PTON)
      File "/usr/lib/python2.7/site-packages/netaddr/ip/__init__.py", line 281, in __init__
        % self.__class__.__name__)
    ValueError: IPAddress() does not support netmasks or subnet prefixes! See documentation for details.
    Created symlink from /etc/systemd/system/httpd.service to /usr/lib/systemd/system/apache2.service.
    Created symlink from /etc/systemd/system/apache.service to /usr/lib/systemd/system/apache2.service.
    Created symlink from /etc/systemd/system/multi-user.target.wants/apache2.service to /usr/lib/systemd/system/apache2.service.

eth0      Link encap:Ethernet  HWaddr 00:1A:4A:16:02:85  
          inet addr:10.162.220.101  Bcast:10.162.220.255  Mask:255.255.255.0
          inet6 addr: fe80::21a:4aff:fe16:285/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:24615 errors:0 dropped:0 overruns:0 frame:0
          TX packets:7018 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:41191663 (39.2 Mb)  TX bytes:955697 (933.2 Kb)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:3310 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3310 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:827415 (808.0 Kb)  TX bytes:827415 (808.0 Kb)}}

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.162.220.254  0.0.0.0         UG    0      0        0 eth0
10.162.220.0    0.0.0.0         255.255.255.0   U     0      0        0 eth0