[2.9.1-rc2] cannot install snap

[Marian Gasparovic]

Our test jobs failed on snap install failure

error: cannot perform the following tasks:
- Run install hook of "maas" snap if present (run hook "install":
-----
Traceback (most recent call last):
  File "/snap/maas/11178/bin/maas", line 8, in <module>
    sys.exit(main())
  File "/snap/maas/11178/lib/python3.8/site-packages/maascli/__init__.py", line 39, in main
    parser = prepare_parser(argv)
  File "/snap/maas/11178/lib/python3.8/site-packages/maascli/parser.py", line 75, in prepare_parser
    register_cli_commands(parser)
  File "/snap/maas/11178/lib/python3.8/site-packages/maascli/cli.py", line 274, in register_cli_commands
    django_setup()
  File "/snap/maas/11178/usr/lib/python3/dist-packages/django/__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/snap/maas/11178/usr/lib/python3/dist-packages/django/apps/registry.py", line 114, in populate
    app_config.import_models()
  File "/snap/maas/11178/usr/lib/python3/dist-packages/django/apps/config.py", line 211, in import_models
    self.models_module = import_module(models_module_name)
  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/snap/maas/11178/lib/python3.8/site-packages/maasserver/models/__init__.py", line 107, in <module>
    from maasserver.models.bmc import (
  File "/snap/maas/11178/lib/python3.8/site-packages/maasserver/models/bmc.py", line 55, in <module>
    from maasserver.models.node import get_default_zone, Machine, Node
  File "/snap/maas/11178/lib/python3.8/site-packages/maasserver/models/node.py", line 194, in <module>
    from provisioningserver.drivers.power.registry import PowerDriverRegistry
  File "/snap/maas/11178/lib/python3.8/site-packages/provisioningserver/drivers/power/registry.py", line 9, in <module>
    from provisioningserver.drivers.pod.registry import PodDriverRegistry
  File "/snap/maas/11178/lib/python3.8/site-packages/provisioningserver/drivers/pod/registry.py", line 10, in <module>
    from provisioningserver.drivers.pod.lxd import LXDPodDriver
  File "/snap/maas/11178/lib/python3.8/site-packages/provisioningserver/drivers/pod/lxd.py", line 11, in <module>
    from pylxd import Client
  File "/snap/maas/11178/usr/lib/python3/dist-packages/pylxd/__init__.py", line 19, in <module>
    from pylxd.client import Client,EventType # NOQA
  File "/snap/maas/11178/usr/lib/python3/dist-packages/pylxd/client.py", line 21, in <module>
    import requests_unixsocket
ModuleNotFoundError: No module named 'requests_unixsocket'

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