Removing the version/displayVersion distinction

[William Lachance]

Hey,

For historical reasons, we've had a "display version" for Firefox which
differs from the actual "version". In actual practice, these versions
are always the same *except* on beta where the version is "64.0" vs.
"64.0bXX".

https://firefox-source-docs.mozilla.org/toolkit/components/telemetry/telemetry/data/environment.html

This distinction has caused me a lot of grief when working on tools like
mission control (https://missioncontrol.telemetry.mozilla.com): most of
our telemetry uses the version, but the beta number is actually critical
to quickly understanding what versions are affected/not affected by a
bug or problem. In practice, this means that I often have to submit
patches and dig deep into our build system and telemetry etl code to
make things work. The most recent example is this bug:

https://bugzilla.mozilla.org/show_bug.cgi?id=1510431

I had a conversation about this with Chris AtLee a couple of weeks ago
and as far as we can tell, this distinction has no actual business
value: the display version is the one we always want to use for our
internal systems. Thus, I'd like to just remove it for future releases
and make the display version *equal* the version, always. We probably
can't take the displayVersion out altogether (that would break a lot of
things), unfortunately, but we can make the practical distinction
irrelevant for future releases of Firefox.

If there are no objections or concerns, I would like to file a bug to
remove the option in the build system to specify a separate display
version, and make the version field equal to the display version while
updating the release bumping code to match.

Q & A:

Q: What versions of Firefox would this affect?
A: Only beta. Release and nightly always have the same display version
and version (XX.0.X in the case of release, XX.0a1 in the case of nightly).

Q: Would this affect release candidate builds on beta at all?
A: No. Release candidates always have the same display version as the
plain version (i.e. 64.0).

Q: Can't you just derive the display version using the buildid?
A: Yes, but this implies additional work and complexity for every
system, the exact problem I'm trying to solve here.

Will

[jw...@mozilla.com]

I should note that this also would affect ESR since version_display there is stuff like 60.0.2esr

And this does have some impact on things like addon compat matrix and AMO in terms of what extensions can be compatible with which versions [when strict compat mode is enabled] (a technical problem and would need some investigation for sure).

Beyond that every other concern I have is proxied from past conversations and opinions expressed by community and employees and not a direct concern of my own so I'll defer it to others to weigh in on if still an issue.

~Justin Wood (Callek)