New comment by tornaria on void-packages repository

https://github.com/void-linux/void-packages/pull/43946#issuecomment-1562016558

Comment:
This PR fixes the first time check is run, but not the second and subsequent runs.

In fact, the wheel will be installed into a different testdir each time (and not removed afterwards) and this only ignores the current one.

Suggestions:
 - use `testdir=$(mktemp -d)` so the testdir is outside the wrksrc tree.
 - use `--ignore=${wrksrc}/tmp` so we ignore all installations.