Previously, -nodebug cleared all prior -debug configurations in the
command line while allowing subsequent debug options to be applied.
However, -debug=0 and -debug=none completely disabled debugging,
even for categories specified afterward.
This commit ensures consistency by making -debug=0 and -debug=none
behave like -nodebug: they now clear previously set debug configurations
but do not disable debugging for categories specified later.
Co-Authored-By: Ryan Ofsky <ryan@ofsky.org>
