On Ubuntu Hirsute (minimum installation) with the system guix package:
$ HOSTS=x86_64-linux-gnu ./contrib/guix/guix-build.sh
make: Entering directory '/home/hebasto/bitcoin/depends'
make[1]: Entering directory '/home/hebasto/bitcoin/depends'
Checksum missing or mismatched for boost source. Forcing re-download.
Fetching boost_1_71_0.tar.bz2 from https://dl.bintray.com/boostorg/release/1.71.0/source/
/bin/sh: 1: curl: not found
Fetching boost_1_71_0.tar.bz2 from https://bitcoincore.org/depends-sources
/bin/sh: 1: curl: not found
make[1]: *** [funcs.mk:276: /home/hebasto/bitcoin/depends/sources/download-stamps/.stamp_fetched-boost-boost_1_71_0.tar.bz2.hash] Error 127
make[1]: Leaving directory '/home/hebasto/bitcoin/depends'
make: *** [Makefile:281: download-linux] Error 2
make: Leaving directory '/home/hebasto/bitcoin/depends'
This PR fixes that issue.