I found emacs-pyim failed to build because guix builder cannot download
source from GNU ELPA.

I check the page of pyim https://elpa.gnu.org/packages/pyim.html, and
found that GNU ELPA only provides .tar.lz format source for old version
of package.

If GNU ELPA no longer provides stable url for packages, we may need to
adjust elpa importer to use Git repo if possible. And we also need to
fix packages depend on GNU ELPA url because they may be broken in future.
-- 
Retrieve my PGP public key:

  gpg --recv-keys D47A9C8B2AE3905B563D9135BE42B352A9F6821F

Zihao