distutils.FancyGetopt does not hadle repeating options with argument

setuptools inherits command line parsing from distutils which uses the distutils.FancyGetopt class for setting up and performing the parsing. Documentation and comments in the code suggest that it exists a way to specify command line options that can be repeated. However, trying to use this facility for options that take arguments results in only the last specified argument to be retained. It works as expected for boolean options. I believe this is a bug that went so far unnoticed because the code base uses this feature only for the --verbose option which does not take arguments.

I know setuptools is moving away from command line invocation and toward a more declarative style. Is there any motivation to fix this? The patch for making distutils.FancyGetopt.getopt() do the right thing for repeated options with argumentsis just a few lines and I can submit a PR.

I currently monkey patch the method in my project. Some more monkey patching when it comes to setuptools does not even look that bad ;)

Start at the distutils.FancyGetopt.getopt() method named in the issue and inspect how repeated options with arguments are stored, contrasting them with boolean options. Confirm the behavior with a focused regression check: repeated argument-bearing options should retain each specified argument, while existing boolean-option behavior remains unchanged.