ubuntu-release-upgrader-core does not depend on gnupg in Ubuntu 16.04

[Jens Elkner]

> + do-release-upgrade
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [819 B]
Get:2 Upgrade tool [1,263 kB]
Fetched 1,264 kB in 0s (0 B/s)
authenticate 'bionic.tar.gz' against 'bionic.tar.gz.gpg'
Traceback (most recent call last):
  File "/usr/bin/do-release-upgrade", line 200, in <module>
    fetcher.run()
  File "/usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeFetcherCore.py", line 282, in run
    if not self.authenticate():
  File "/usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeFetcherCore.py", line 76, in authenticate
    if self.gpgauthenticate(f, sig):
  File "/usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeFetcherCore.py", line 108, in gpgauthenticate
    close_fds=False, universal_newlines=True)
  File "/usr/lib/python3.5/subprocess.py", line 947, in __init__
    restore_signals, start_new_session)
  File "/usr/lib/python3.5/subprocess.py", line 1551, in _execute_child
    raise child_exception_type(errno_num, err_msg)
FileNotFoundError: [Errno 2] No such file or directory: 'gpg'

> lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.5 LTS
Release: 16.04
Codename: xenial

> + apt dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

> which gpg
gpg: Command not found.

> which gpg2
/usr/bin/gpg2

[Brian Murray (brian-murray)]

ubuntu-release-upgrader does not have an explicit dependency on gnupg, but gnupg is part of the daily-live seed and is part of the minimal task for xenial.