Yeah I think the master for git comes from mastering/master-image/master-tape which comes from the master = main/leading definition which doesn't necessarily imply a connection to master/slave. The black/white list seems to be more out of a day/light/dawn = good/pure/safe and night/dark/dusk = bad/corrupt/dangerous theme common to many cultures.

Either way though, can't really go wrong with more descriptive/functional names.