prompt to upgrade to 18.04 shows while upgrade to 16.04 is still in progress

[Steve Langasek]

While upgrading a desktop system from 14.04 to 16.04 over the holidays, I was prompted to upgrade to 18.04... while the upgrade to 16.04 was still running.

I don't know what would happen if I clicked 'yes', but I'm sure it wouldn't DTRT.

[Steve Langasek (vorlon)]

Screenshot.

[Brian Murray (brian-murray)]

There is a RELEASE_UPGRADE_IN_PROGRESS environmental variable which gets set to 1 when the release upgrade starts but it was check-new-release-gtk that presented the dialog so we'll need a different way to denote that a release upgrade is already happening.

[Brian Murray (brian-murray)]

I went ahead and tested this to see what would happen if I did click 'yes' on the upgrade prompt to Ubuntu 18.04. As the team suspected the upgrade to 18.04 failed because it was unable to get an exclusive lock, so while this is ugly it won't actually break anybody. Additionally, if I recall correctly the release upgrade prompt is on a timer so if somebody received a prompt to upgrade to the next release and clicked 'yes' they shouldn't receive a prompt to upgrade to the next next release. Attached you find a screenshot of the ugly.

And for future reference to recreate this I manually ran check-new-release-gtk a couple of times while the upgrade was in process (i.e. after the downloading phase) until it finally worked.