This commit includes a variety of different non-destructive fixes and
formatting as recommended by shellcheck and by ruff's check/format.
Fixes include things like double quoting vars to prevent space issues,
variety of line formatting in python files, and removing of unused
imports
* when bind-mounting, resolve any symlinks ($v/) and read target inode;
for example merged /bin and /usr/bin
* add failsafe in case this test should break in new exciting ways;
inspect `mount` for any instances of the jailed path
(not /proc/mounts since that has funny space encoding)
* unmount in a while-loop because xargs freaks out if one of them fail
* and systemd doesn't give us a /dev/stderr to write to anyways