I hit an edge case when using Private Wi-Fi addressing on macOS where
the last section of the randomized mac address starts with a '0'. The
hostname parsing for the shell integration didn't handle this case, so
issue #2512 reappeared.
This fixes that by explicitly handling port numbers < 10.
Note that this includes some failing tests because I want to make the
uri handling better and more specific. It's a little bit too general
right now so I want to lock it down to:
1. macOS only; and
2. valid mac address values
because that's how the macOS private Wi-Fi address thing works;
randomizes your mac address and sets that as your hostname.
