Virtual Chassis Mastership addition automatically changes device vc_position, breaking backup/restore of DB

[alejandrosalinas]

Issue type

[ ] Feature request
[X] Bug report
[ ] Documentation

Environment

• Python version: 3.6
• NetBox version: 2.3.3

Description

Upon creating a Virtual Chassis the position of the master gets updated to 1, causing a conflict whenever this was not the device 1 of the chassis (Example: Juniper fpc0 device being the master). This auto-update breaks backup and restore of the database.

Steps to replicate (using pynetbox for simplicity). First I create two devices and the virtual chassis

In [126]: deviceA_dict = nb.dcim.devices.create(**deviceA_data)
In [127]: deviceA_dict['vc_position']
Out[127]: 0

In [128]: deviceB_dict = nb.dcim.devices.create(**deviceB_data)
In [129]: deviceB_dict['vc_position']
Out[129]: 1

In [131]: vc_dict = nb.dcim.virtual_chassis.create({'domain': 'someVCname', 'master': deviceA_dict['id']})

In [132]: deviceA_obj = nb.dcim.devices.get(name='deviceA')
In [133]: deviceA_obj.vc_position
Out[133]: 1   <=== device position got changed

After this, using the GUI I manually moved deviceA to have position 0 and added deviceB to the cluster as I intended originally

In [161]: deviceA_obj = nb.dcim.devices.get(name='deviceA')
In [162]: deviceA_obj.vc_position
Out[162]: 0
In [163]: deviceA_obj.virtual_chassis.id
Out[163]: 1

In [164]: deviceB_obj = nb.dcim.devices.get(name='deviceB')
In [165]: deviceB_obj.vc_position
Out[165]: 1
In [166]: deviceB_obj.virtual_chassis.id
Out[166]: 1

In [167]: vc_obj = nb.dcim.virtual_chassis.get(domain="someVCname")
In [168]: deviceB_obj.virtual_chassis.master
Out[168]: deviceA

And now backup and restore breaks because of the vc_id, position constraint

[user@netboxserver:netbox] python manage.py dumpdata >  ~/VCtest.json
[user@netboxserver:netbox] python manage.py flush --noinput
[user@netboxserver:netbox] python manage.py loaddata ~/VCtest.json
Traceback (most recent call last):
  File "/var/netbox_env/lib/python3.6/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
psycopg2.IntegrityError: duplicate key value violates unique constraint "dcim_device_virtual_chassis_id_vc_position_efea7133_uniq"
DETAIL:  Key (virtual_chassis_id, vc_position)=(1, 1) already exists.