docker.test.yml: Escape $$exit_status
docker.test.yml: Escape $$exit_status

The dollar sign needs to be escaped, otherwise it's interpreted by Docker-Compose.
https://github.com/docker/compose/blob/master/docs/compose-file.md#variable-substitution

SuperNEMO-DBD/cadfaelbrew,saketkc/linuxbrew,Linuxbrew/linuxbrew,saketkc/linuxbrew,Homebrew/linuxbrew,Angeldude/linuxbrew,Linuxbrew/linuxbrew,SuperNEMO-DBD/cadfaelbrew,gnubila-france/linuxbrew,reelsense/linuxbrew,Homebrew/linuxbrew,gnubila-france/linuxbrew,gnubila-france/linuxbrew,Angeldude/linuxbrew,reelsense/linuxbrew,Linuxbrew/linuxbrew,Homebrew/linuxbrew,saketkc/linuxbrew,Angeldude/linuxbrew,reelsense/linuxbrew,sjackman/linuxbrew,sjackman/linuxbrew,reelsense/linuxbrew,saketkc/linuxbrew,gnubila-france/linuxbrew,sjackman/linuxbrew,SuperNEMO-DBD/cadfaelbrew,Linuxbrew/linuxbrew,sjackman/linuxbrew,Angeldude/linuxbrew,SuperNEMO-DBD/cadfaelbrew,Homebrew/linuxbrew