When using origin instead of install_sources install hook fails

Landscape-client rev 33
Ubuntu xenial

When using the deprecated "origin" set to:

$ juju config landscape-client origin
deb http://ppa.launchpad.net/landscape/17.03/ubuntu xenial main

Install hook failed with:

2021-01-14 08:35:50 DEBUG install After this operation, 17.4 MB of additional disk space will be used.
2021-01-14 08:35:50 DEBUG install WARNING: The following packages cannot be authenticated!
2021-01-14 08:35:50 DEBUG install landscape-common landscape-client
2021-01-14 08:35:50 DEBUG install E: There were unauthenticated packages and -y was used without --allow-unauthenticated
2021-01-14 08:35:50 DEBUG install Traceback (most recent call last):
2021-01-14 08:35:50 DEBUG install File "/var/lib/juju/agents/unit-landscape-client-1035/charm/hooks/install", line 59, in <module>
2021-01-14 08:35:50 DEBUG install sys.exit(hooks.execute(sys.argv))
2021-01-14 08:35:50 DEBUG install File "/var/lib/juju/agents/unit-landscape-client-1035/charm/hooks/charmhelpers/core/hookenv.py", line 934, in execute
2021-01-14 08:35:50 DEBUG install self._hooks[hook_name]()
2021-01-14 08:35:50 DEBUG install File "/var/lib/juju/agents/unit-landscape-client-1035/charm/hooks/install", line 25, in install
2021-01-14 08:35:50 DEBUG install fetch.apt_install(['landscape-client'], fatal=True)
2021-01-14 08:35:50 DEBUG install File "/var/lib/juju/agents/unit-landscape-client-1035/charm/hooks/charmhelpers/fetch/ubuntu.py", line 276, in apt_install
2021-01-14 08:35:50 DEBUG install _run_apt_command(cmd, fatal)
2021-01-14 08:35:50 DEBUG install File "/var/lib/juju/agents/unit-landscape-client-1035/charm/hooks/charmhelpers/fetch/ubuntu.py", line 770, in _run_apt_command
2021-01-14 08:35:50 DEBUG install retry_message="Couldn't acquire DPKG lock")
2021-01-14 08:35:50 DEBUG install File "/var/lib/juju/agents/unit-landscape-client-1035/charm/hooks/charmhelpers/fetch/ubuntu.py", line 748, in _run_with_retries
2021-01-14 08:35:50 DEBUG install result = subprocess.check_call(cmd, env=env)
2021-01-14 08:35:50 DEBUG install File "/usr/lib/python3.5/subprocess.py", line 581, in check_call
2021-01-14 08:35:50 DEBUG install raise CalledProcessError(retcode, cmd)
2021-01-14 08:35:50 DEBUG install subprocess.CalledProcessError: Command '['apt-get', '--assume-yes', '--option=Dpkg::Options::=--force-confold', 'install', 'landscape-client']' returned non-zero exit status 100
2021-01-14 08:35:50 ERROR juju.worker.uniter.operation runhook.go:132 hook "install" failed: exit status 1
2021-01-14 08:35:50 DEBUG juju.machinelock machinelock.go:186 machine lock released for uniter (run install hook)
2021-01-14 08:35:50 DEBUG juju.worker.uniter.operation executor.go:74 lock released
2021-01-14 08:35:50 INFO juju.worker.uniter resolver.go:126 awaiting error resolution for "install" hook
2021-01-14 08:35:50 DEBUG juju.worker.uniter agent.go:20 [AGENT-STATUS] error: hook failed: "install"
2021-01-14 08:35:50 INFO juju.worker.uniter resolver.go:126 awaiting error resolution for "install" hook

This was fixed using install sources instead:
$ juju config landscape-client install_sources=”ppa:landscape/17.03”
$ juju resolve landscape-client/1035

and install hook completed with no issues.