snappy versions tracebacks on lack of network

[Martin Albisetti]

ubuntu@localhost:~$ snappy versions
Traceback (most recent call last):
  File "/usr/bin/snappy", line 9, in <module>
    status = Main().__main__()
  File "/usr/lib/python3/dist-packages/snappy/main.py", line 159, in __main__
    return callback(args)
  File "/usr/lib/python3/dist-packages/snappy/main.py", line 263, in _do_versions
    ClickDataSource().versions(all))
  File "/usr/lib/python3/dist-packages/snappy/click.py", line 74, in versions
    all_updates_list = repo.get_upgradable()
  File "/usr/lib/python3/dist-packages/click/repository.py", line 183, in get_upgradable
    headers={"content-type": "application/json"})
  File "/usr/lib/python3/dist-packages/click/network.py", line 70, in http_request
    curl.perform()
pycurl.error: (6, 'Could not resolve host: myapps.developer.ubuntu.com')

[Alexander Sack (asac)]

mvo: another error case for our error handling on console thread for console experience

[Michael Vogt (mvo)]

Current version behave better:

root@localhost:~# ifconfig eth0 down
root@localhost:~# snappy list -u
Get https://system-image.ubuntu.com//ubuntu-core/devel-proposed/generic_amd64/index.json: dial tcp: lookup system-image.ubuntu.com: no such host