phablet@ubuntu-phablet:~$ sudo system-image-cli -v -i
[sudo] password for phablet:
b'54224609\n'
[systemimage] Nov 14 18:40:49 2018 (7184) Couldn't open time offset file, assuming zero offset.
current build number: 22
device name: FP2
channel: ubports-touch/16.04/rc
last update: 1970-06-04 03:39:10
version version: 22
version ubports: 20181113-1138
version tag: 2018-W46
version keyring: archive-master
version device: 20181113-25695
phablet@ubuntu-phablet:~$ sudo system-image-cli -vv --switch ubports-touch/15.04/stable
b'54224609\n'
[systemimage] Nov 14 18:41:59 2018 (7303) running state machine [ubports-touch/15.04/stable/FP2]
[systemimage] Nov 14 18:41:59 2018 (7303) -> [ 1] _cleanup
[systemimage] Nov 14 18:41:59 2018 (7303) -> [ 2] _get_blacklist_1
[systemimage] Nov 14 18:41:59 2018 (7303) Looking for blacklist: https://system-image.ubports.com/gpg/blacklist.tar.xz
[systemimage] Nov 14 18:41:59 2018 (7303) [0xb60bc8d0] Requesting group download:
        https://system-image.ubports.com/gpg/blacklist.tar.xz -> /var/lib/system-image/keyring.tar.xz
        https://system-image.ubports.com/gpg/blacklist.tar.xz.asc -> /var/lib/system-image/keyring.tar.xz.asc

[systemimage] Nov 14 18:42:00 2018 (7303) Allow GSM? No
[systemimage] Nov 14 18:42:00 2018 (7303) [/com/canonical/applications/download/com_2eubuntu_2eterminal_5fterminal_5f0_2e9_2e0/c91e098ad453455189207915458958a0] Running group download reactor
[systemimage] Nov 14 18:42:00 2018 (7303) self: <UDMDownloadManager at 0xb60bc8d0>, self._iface: <Interface <ProxyObject wrapping <dbus._dbus.SystemBus (system) at 0xb618d2a0> :1.148 /com/canonical/applications/download/com_2eubuntu_2eterminal_5fterminal_5f0_2e9_2e0/c91e098ad453455189207915458958a0 at 0xb60bc930> implementing 'com.canonical.applications.GroupDownload' at 0xb60bc7d0>
[systemimage] Nov 14 18:42:00 2018 (7303) [/com/canonical/applications/download/com_2eubuntu_2eterminal_5fterminal_5f0_2e9_2e0/c91e098ad453455189207915458958a0] Group download reactor done
[systemimage] Nov 14 18:42:00 2018 (7303) uncaught exception in state machine
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 133, in __next__
    step()
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 219, in _get_blacklist_1
    get_keyring('blacklist', url, 'image-master')
  File "/usr/lib/python3/dist-packages/systemimage/keyring.py", line 107, in get_keyring
    (ascxz_src, ascxz_dst),
  File "/usr/lib/python3/dist-packages/systemimage/download.py", line 209, in get_files
    self._get_files(records, pausable, signal_started)
  File "/usr/lib/python3/dist-packages/systemimage/udm.py", line 189, in _get_files
    missing, local_paths))
AssertionError: Missing destination files: ['/var/lib/system-image/keyring.tar.xz', '/var/lib/system-image/keyring.tar.xz.asc']
local_paths: [dbus.String('/tmp/blacklist.tar.xz'), dbus.String('/tmp/blacklist.tar.xz.asc')]
Exception occurred during update; see log file for details
[systemimage] Nov 14 18:42:00 2018 (7303) system-image-cli exception
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/systemimage/main.py", line 402, in main
    list(state)
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 133, in __next__
    step()
  File "/usr/lib/python3/dist-packages/systemimage/state.py", line 219, in _get_blacklist_1
    get_keyring('blacklist', url, 'image-master')
  File "/usr/lib/python3/dist-packages/systemimage/keyring.py", line 107, in get_keyring
    (ascxz_src, ascxz_dst),
  File "/usr/lib/python3/dist-packages/systemimage/download.py", line 209, in get_files
    self._get_files(records, pausable, signal_started)
  File "/usr/lib/python3/dist-packages/systemimage/udm.py", line 189, in _get_files
    missing, local_paths))
AssertionError: Missing destination files: ['/var/lib/system-image/keyring.tar.xz', '/var/lib/system-image/keyring.tar.xz.asc']
local_paths: [dbus.String('/tmp/blacklist.tar.xz'), dbus.String('/tmp/blacklist.tar.xz.asc')]
[systemimage] Nov 14 18:42:00 2018 (7303) state machine finished