Jack Hill <jackhill@jackhill.us> writes:

> Hi Guix,
>
> I've created the following package definition using the pypi importer. 
> However, when I try to build it with guix build -f … the build fails 
> because it cannot download the source. The downloader gets redirected to a 
> url that returns 404. However, the pypi importer was able download the 
> source.

It seems no proper source tarball is available on PyPI, only a "wheel":

<https://pypi.org/project/mallard-ducktype/>

The importer uses those to extract requirements.txt, and apparently
returns the wheel hash when it fails to find a proper source.  That is
probably a bug.

In this case it is probably easiest to download the source from the
upstream repository, or ask the maintainer to upload a tarball.