Three Dollar Quill

• Wednesday: I fixed some brokenness in the link comparison logic. (Some of pip's internal classes don't implement __eq__.)
• Thursday: I changed up the link comparison logic. I may change it again.
• Friday: I discovered that I'd forgotten to code the wheel tag logic, so I implemented part of it.
• Saturday: I made progress getting rid of invalid tests.
• Sunday: I tried to figure out why the final test was failing, and ended up mostly confused.
• Monday: I figured out what was going wrong with the last test, and implemented the rest of the wheel tag logic.

Next week, I want to take a short break, then work on getting my changes ready for review.