Plain setup.py uploads

I'm trying to follow the directions for doing uploads to devpi using setup.py rather than 'devpi upload' found here: http://doc.devpi.net/1.2.1/userman/devpi_misc.html#using-plain-setup-py-for-... Things are well enough configured that 'devpi upload' works, but trying a command like 'python setup.py sdist --formats=zip upload --repository=myrepo' results in: Upload failed (405): Method Not Allowed Spying on the HTTP traffic, I can see that the request is going to the expected URL and includes an Authorization header with the credentials (encoded for basic auth) from my .pypirc. Is this known to be working in 1.2.1? Any suggestions for tracking down the problem? Thanks, Eric