Path to upgrade 4.2.8 Debian package to 4.4.1 source install?

After thinking about it, I've come to realize that upgrading my test
instance is the best way to go. I can practice upgrading, see if the new
features will be useful on the active instance, and not have to worry about
messing up a source code patch.

I'm on 4.2.8, as that's what you get on Debian if you apt-get install
request-tracker4. The latest release, though, is 4.4.1 I believe. What are
the upgrade steps to upgrade, or am I better off removing RT and starting
with 4.4.1? Either way, how do I keep my existing RT database (MySQL)? I
believe there are db migration commands, but I don't know how they work.
I've googled this, and have come up with only a couple hits, neither of
which was a guide. I could have missed the article(s) people usually use
for this process, of course. How do I upgrade, and/or is there already a
resource people use to do this? Thanks!

-- 
Alex Hall
Automatic Distributors, IT department
[email protected]

---------
RT 4.4 and RTIR training sessions, and a new workshop day! https://bestpractical.com/training
* Boston - October 24-26
* Los Angeles - Q1 2017