The test harness supports injecting extensions via --extra-config-opt.
However, if you do this, various tests that print state about loaded
extensions fail.
This commit teaches the test harness to recognize when custom
extensions are loaded so that tests can use feature sniffing to
conditionalize tests based on that.
Soooooooo I'm dumb and misread this the last couple of times. Should this be doing
if section != 'extensions':
Other than that this is what I was proposing, and I'm not sure how I misread it so badly before. :(