Probably what we most care about is upgrading from the current bundled version to the head and released versions in git.
Yes, and that's the first thing we test indeed when we run the upgrade test.
Is the test just to make sure that an upgrade works properly for people who might have saved images and want to update their asdf in that same image?
I will leave these to Faré to answer...
For people who might have saved an image. For people who are using an old C-L-C that *did* save an image (don't laugh: my work laptop, running a 2010 ubuntu, has c-l-c 6.18 saving an image of clisp or sbcl with ASDF 1.374 from December 2009). For people using require on an old Lisp that provides an old ASDF (e.g. CLISP today still ships with ASDF 2.011 from November 2010). For finding bugs in the ASDF upgrade process itself.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org It is not recognized in the full amplitude of the word that all freedom is essentially self-liberation — that I can have only so much freedom as I procure for myself by my ownness. — Max Stirner