Print script output in case of a failure. (#7759)
Print script output in case of a failure. (#7759)

These tests failed at https://travis-ci.com/certbot/certbot/jobs/285202481 but do not include any output from the script about what went wrong because the string created from `subprocess.CalledProcessError` does not include value of output.

This PR fixes that by printing these values which `pytest` will include in the output if the test fails.
lmcro/letsencrypt,letsencrypt/letsencrypt,letsencrypt/letsencrypt,stweil/letsencrypt,lmcro/letsencrypt,stweil/letsencrypt