I tried with a checked out guix and I got what follows


...
validating RUNPATH of 1 binaries in "/gnu/store/kydnvbnz4vy4b7j2j595jjkc678lvn03-xdg-user-dirs-0.17/bin"...
phase `validate-runpath' succeeded after 0.0 seconds
starting phase `validate-documentation-location'
phase `validate-documentation-location' succeeded after 0.0 seconds
starting phase `delete-info-dir-file'
phase `delete-info-dir-file' succeeded after 0.0 seconds
starting phase `patch-dot-desktop-files'
phase `patch-dot-desktop-files' succeeded after 0.0 seconds
starting phase `install-license-files'
installing 1 license files
phase `install-license-files' succeeded after 0.0 seconds
starting phase `reset-gzip-timestamps'
phase `reset-gzip-timestamps' succeeded after 0.0 seconds
starting phase `compress-documentation'
compressing documentation in '/gnu/store/kydnvbnz4vy4b7j2j595jjkc678lvn03-xdg-user-dirs-0.17/share/man' with "gzip" and flags ("--best" "--no-name")
phase `compress-documentation' succeeded after 0.0 seconds
guix system: error: build failed: error parsing derivation `/gnu/store/dp8ywhh22n8ixikqdvsb6w6qbn4iw899-environment.drv': expected string `Derive(['