bug: Allow UsageError exception to use more specific error code UsageError exception returned 400 error code but should return 405 when generated for a bad http method. Modified error handler to use 400 error code if self.response_code was less then 400. This should reproduce the standard error of 400 if one was not specified and preserve any other explicitly set response code. Also enhanced a test case to verify the 405 is returned.

from roundup.dist.command.build import build_message_files, check_manifest
from setuptools.command.install_lib import install_lib as base

class install_lib(base):

    def run(self):
        check_manifest()
        build_message_files(self)
        base.run(self)