Here's a better comment.

Another flavor of this: https://ci.lscape.net/job/landscape-system-tests/5198

[from landscape-0-inner-logs/glance-simplestreams-sync-0/var/log/juju/unit-glance-simplestreams-sync-0.log]
2017-02-06 15:25:41 INFO install Cannot add PPA: 'ppa:~landscape/ubuntu/glance-simplestreams-sync'.
2017-02-06 15:25:41 INFO install The team named '~landscape' has no PPA named 'ubuntu/glance-simplestreams-sync'
2017-02-06 15:25:41 INFO install Please choose from the following available PPAs:
2017-02-06 15:25:41 INFO install  * '14.10':  LDS 14.10
2017-02-06 15:25:41 INFO install  * '15.01':  LDS 15.01
2017-02-06 15:25:41 INFO install  * '15.01-proxy':  LDS 15.01 with proxy test
2017-02-06 15:25:41 INFO install  * '15.10':  LDS 15.10
2017-02-06 15:25:41 INFO install  * '15.10-proxy':  LDS 15.10 with proxy test
2017-02-06 15:25:41 INFO install  * '15.11':  LDS 15.11
2017-02-06 15:25:41 INFO install  * '16.03':  LDS 16.03
2017-02-06 15:25:41 INFO install  * '16.06':  LDS 16.06
2017-02-06 15:25:41 INFO install  * 'fake-kernel':  fake kernel
2017-02-06 15:25:41 INFO install  * 'glance-simplestreams-sync':  glance simplestreams sync
2017-02-06 15:25:41 INFO install  * 'landscape-api':  Landscape API client
2017-02-06 15:25:41 INFO install  * 'landscape-api-staging':  Landscape API client staging
2017-02-06 15:25:41 INFO install  * 'landscape-client-cloud-installer':  Landscape Client for the LDS Cloud Installer
2017-02-06 15:25:41 INFO install  * 'lds-demo':  LDS Demo
2017-02-06 15:25:41 INFO install  * 'lds-preview':  LDS Preview
2017-02-06 15:25:41 INFO install  * 'maas-1.8.2-fix-1576253':  MAAS 1.8.2 packages for #1576253
2017-02-06 15:25:41 INFO install  * 'opendaylight-0.2.3':  OpenDaylight Helium 0.2.3
2017-02-06 15:25:41 INFO install  * 'opendaylight-0.2.4':  OpenDalight Helium 0.2.4 SR4
2017-02-06 15:25:41 INFO install  * 'production':  Landscape client production packages
2017-02-06 15:25:41 INFO install  * 'staging':  Landscape client staging packages
2017-02-06 15:25:41 INFO install  * 'trunk':  Landscape client trunk packages
2017-02-06 15:25:41 INFO install  * 'txjuju-daily':  txjuju daily builds
2017-02-06 15:25:41 INFO install Traceback (most recent call last):
2017-02-06 15:25:41 INFO install   File "/var/lib/juju/agents/unit-glance-simplestreams-sync-0/charm/hooks/install.real", line 290, in <module>
2017-02-06 15:25:41 INFO install     hooks.execute(sys.argv)
2017-02-06 15:25:41 INFO install   File "/var/lib/juju/agents/unit-glance-simplestreams-sync-0/charm/hooks/charmhelpers/core/hookenv.py", line 704, in execute
2017-02-06 15:25:41 INFO install     self._hooks[hook_name]()
2017-02-06 15:25:41 INFO install   File "/var/lib/juju/agents/unit-glance-simplestreams-sync-0/charm/hooks/install.real", line 206, in install
2017-02-06 15:25:41 INFO install     add_source(hookenv.config('source'), hookenv.config('key'))
2017-02-06 15:25:41 INFO install   File "/var/lib/juju/agents/unit-glance-simplestreams-sync-0/charm/hooks/charmhelpers/fetch/__init__.py", line 281, in add_source
2017-02-06 15:25:41 INFO install     subprocess.check_call(['add-apt-repository', '--yes', source])
2017-02-06 15:25:41 INFO install   File "/usr/lib/python2.7/subprocess.py", line 541, in check_call
2017-02-06 15:25:41 INFO install     raise CalledProcessError(retcode, cmd)
2017-02-06 15:25:41 INFO install subprocess.CalledProcessError: Command '['add-apt-repository', '--yes', u'ppa:landscape/glance-simplestreams-sync']' returned non-zero exit status 1
2017-02-06 15:25:41 ERROR juju.worker.uniter.operation runhook.go:107 hook "install" failed: exit status 1

Notice that the missing PPA is included in the list. Looks like a transient failure to find the PPA, but it worked when the error path queried launchpad for the list of PPAs for the landscape user.