Help with setuptools-related build break

[Martin Kelly <martin@martingkelly.com>]

Hi,

I'm attempting to release a new version of my package python-gmpy2 [1] 
and am hitting a bug that I can't figure out how to resolve. 
Specifically, in the latest version under pbuilder, python-setuptools is 
missing. When I add python-setuptools and python3-setuptools it to the 
build dependencies, I get the following error:

Err http://cdn-fastly.deb.debian.org/debian sid/main amd64 
python-pkg-resources all 39.2.0-1
  404  Not Found [IP: 151.101.52.204 80]
Err http://cdn-fastly.deb.debian.org/debian sid/main amd64 
python-setuptools all 39.2.0-1
  404  Not Found [IP: 151.101.52.204 80]
Err http://cdn-fastly.deb.debian.org/debian sid/main amd64 
python3-setuptools all 39.2.0-1
  404  Not Found [IP: 151.101.52.204 80]
E: Failed to fetch 
http://cdn-fastly.deb.debian.org/debian/pool/main/p/python-setuptools/python-pkg-resources_39.2.0-1_all.deb: 
404  Not Found [IP: 151.101.52.204 80]
E: Unable to fetch some packages; try '-o APT::Get::Fix-Missing=true' to 
continue with missing packages

[snip]

E: pbuilder-satisfydepends failed.

Indeed, this package version does not exist in the repo, so I'm not sure 
why apt is attempting to install it.

Does anyone have some guidance and/or debugging suggestions?

Thanks,
Martin

[1] https://salsa.debian.org/python-team/modules/python-gmpy2