Figuring out what was going on with pip took a little longer than I would have liked, because I wrote the test wrong. Once I figured out the correct test, I was able to put together an extremely simple fix that I don't like because it seems to me like it breaks reasonable assumptions about how the code works. The alternatives I looked into, I either couldn't figure out how to do, or they simply didn't work. All the same, I'm not yet comfortable committing to the way I've found that does work.
Hopefully, I'll decide on something in the next few days. I won't focus completely on that; I've got some other projects that I want to see how they shake out. I've got some other other stuff I want to take care of soon, so I'll call this entry here.