From the log at <https://hydra.gnu.org/build/2389799>:

[...]
FAIL: tests/guix-register.sh
PASS: tests/guix-gc.sh
PASS: tests/guix-daemon.sh
============================================================================
Testsuite summary for GNU Guix 0.14.0-1.ad4953b
============================================================================
# TOTAL: 747
# PASS:  714
# SKIP:  32
# XFAIL: 0
# FAIL:  1
# XPASS: 0
# ERROR: 0
[...]

I restarted the build.