Behaviour change on hyphen in package names with build 1.2.x?

[HubTou]

I think I noticed a behaviour change with build releases 1.2.x.

It seems that hyphen in package names are now replaced with underscore in the .tar.gz distribution files.

I documented this in another PR.

[layday]

This is correct according to the sdist spec - filename segments are separated by hyphens and dist names are normalised, replacing hyphens with underscores. Assuming you are using setuptools, the change you are observing is pypa/setuptools#3593, and is unrelated to build.