ValueError on certain slug filters

[jeremystretch]

Issue type

[ ] Feature request
[x] Bug report
[ ] Documentation

Environment

• Python version: 3.5.2
• NetBox version: 2.2.3

Description

Work on #1649 introduced a regression which yields a ValueError for the following slug filters:

• circuit.tenant
• region.parent
• site.region
• site.tenant
• rack.group
• rack.tenant
• rack.role
• rackreservation.group
• device.tenant
• device.platform
• vrf.tenant
• prefix.vrf
• prefix.tenant
• preifx.site
• preifx.role
• ipaddress.vrf
• ipaddress.tenant
• vlangroup.site
• vlan.site
• vlan.group
• vlan.tenant
• vlan.role
• tenant.group
• cluster.group
• virtualmachine.cluster_group
• virtualmachine.role
• virtualmachine.tenant
• virtualmachine.platform

An example error is:

ValueError at /api/ipam/prefixes/
invalid literal for int() with base 10: 'site1'