Recognise a virtualenv by pyvenv.cfg, not by its nameThe previous commit skipped .venv and venv, which missed the two the repositorymakes itself: the setup scripts create validator_env and miner_env, and.gitignore lists several more names again. Matching names was always going tomiss the next one.A virtualenv is now identified by the pyvenv.cfg it contains, so any name iscovered. Dangling symlinks are skipped rather than raising as well, since a linkpointing outside the repository cannot belong in a wheel and letting copytreefail on one turns any stray file into an error here.The test missed this because it built exactly one .venv. It now covers the realnames, an arbitrary one so name matching cannot come back, and a stray danglingsymlink on its own.