The optparse library is currently marked in the documentation as deprecated in favor of argparse.  However, argparse uses a nonstandard reinterpretation of Unix command line grammars that makes certain arguments impossible to express, and causes scripts to break when ported from optparse to argparse.  See the bug report I filed nine years ago:

https://bugs.python.org/issue9334
argparse does not accept options taking arguments beginning with dash (regression from optparse)

The conclusion of the core developers (e.g. msg309691) seems to have been that although it’s a valid bug, it can’t or won’t be fixed with the current argparse architecture.

I was asked by another core developer to file a bug report for the de-deprecation of optparse (https://discuss.python.org/t/pep-594-removing-dead-batteries-from-the-standard-library/1704/20), so here it is.