/gnu/tests/

u/tests/audio.scm (run-mpd-test): Replace (exit (= ...)) idiom by (test-runner-current (system-test-runner)). * gnu/tests/base.scm (run-basic-test) (run-cleanup-test, run-mcron-test, run-nss-mdns-test): Likewise. * gnu/tests/ci.scm (run-laminar-test): Likewise. * gnu/tests/cups.scm (run-cups-test): Likewise. * gnu/tests/databases.scm (run-memcached-test) (run-postgresql-test, run-mysql-test): Likewise. * gnu/tests/desktop.scm (run-elogind-test): Likewise. * gnu/tests/dict.scm (run-dicod-test): Likewise. * gnu/tests/docker.scm (run-docker-test): Likewise. (run-docker-system-test): Likewise. * gnu/tests/file-sharing.scm (run-transmission-daemon-test): Likewise. * gnu/tests/ganeti.scm (run-ganeti-test): Likewise. * gnu/tests/guix.scm (run-guix-build-coordinator-test): Likewise. (run-guix-data-service-test): Likewise. * gnu/tests/ldap.scm (run-ldap-test): Likewise. * gnu/tests/linux-modules.scm (run-loadable-kernel-modules-test-base): Likewise. * gnu/tests/mail.scm (run-opensmtpd-test) (run-exim-test, run-dovecot-test, run-getmail-test): Likewise. * gnu/tests/messaging.scm (run-xmpp-test) (run-bitlbee-test, run-quassel-test): Likewise. * gnu/tests/monitoring.scm (run-prometheus-node-exporter-server-test) (run-zabbix-server-test): Likewise. * gnu/tests/networking.scm (run-inetd-test, run-openvswitch-test) (run-dhcpd-test, run-tor-test, run-iptables-test, run-ipfs-test): Likewise. * gnu/tests/nfs.scm (run-nfs-test) (run-nfs-server-test, run-nfs-root-fs-test): Likewise. * gnu/tests/package-management.scm (run-nix-test): Likewise. * gnu/tests/reconfigure.scm (run-switch-to-system-test) (run-upgrade-services-test, run-install-bootloader-test): Likewise. * gnu/tests/rsync.scm (run-rsync-test): Likewise. * gnu/tests/security-token.scm (run-pcscd-test): Likewise. * gnu/tests/singularity.scm (run-singularity-test): Likewise. * gnu/tests/ssh.scm (run-ssh-test): Likewise. * gnu/tests/telephony.scm (run-jami-test): Likewise. * gnu/tests/version-control.scm (run-cgit-test): Likewise. (run-git-http-test, run-gitolite-test, run-gitile-test): Likewise. * gnu/tests/virtualization.scm (run-libvirt-test, run-childhurd-test): Likewise. * gnu/tests/web.scm (run-webserver-test, run-php-fpm-test) (run-hpcguix-web-server-test, run-tailon-test, run-patchwork-test): Likewise.