This is a blocking bug for anyone who would like to try Guix from the
git repository, so I'd like to have this fixed in master. WDYT ?
It can still be found at mirror://sourceforge/libpng/zlib-1.2.7.tar.gz.
So for the moment I would suggest changing the ‘uri’ field to a list:
(origin
(method url-fetch)
(uri (list (string-append "http://zlib.net/zlib-"
version ".tar.gz")
(string-append "mirror://sourceforge/libpng/zlib-"
version ".tar.gz")))
(sha256
(base32
"1i96gsdvxqb6skp9a58bacf1wxamwi9m9pg4yn7cpf7g7239r77s")))