Ubuntu 14.04 (trusty) support clarified

[benjaoming]

I don't know if this will be documented, but leaving it here for now:

• Trusty is end-of-life and we do not recommend using it
• Kolibri can run on Trusty but we do not know when the support will be discontinued, but it will
• An issue was fixed in 2018 that may prevent our packages from Buildkite from working: You have to run apt upgrade after installing Trusty to upgrade. This also requires trusty-updates repo to be enabled.
• Trusty has Python 3.4 and relies on the bundled cryptography library. The python3-cryptography package does not exist for Trusty.

Upstream fix: https://bugs.launchpad.net/ubuntu/+source/dpkg/+bug/1730627/comments/19

Well-known error looks like this:

test@ubuntu:~$ sudo dpkg -i buildkite-kolibri_0.13.1-0ubuntu1_all.deb
dpkg-deb: error: archive 'buildkite-kolibri_0.13.1-0ubuntu1_all.deb' has premature member 'control.tar.xz' before 'control.tar.gz', giving up
dpkg: error processing archive buildkite-kolibri_0.13.1-0ubuntu1_all.deb (--install):
 subprocess dpkg-deb --control returned error exit status 2
Errors were encountered while processing:
 buildkite-kolibri_0.13.1-0ubuntu1_all.deb