Fixes <https://bugs.gnu.org/46967>. * guix/utils.scm (decompressed-port): Call 'make-zlib-input-port' instead of invoking %GZIP. (compressed-output-port): Call 'make-zlib-output-port' instead of invoking %GZIP. * doc/guix.texi (Requirements): Require Guile-zlib >= 0.1.0.