Routinator serial number fetch broken

[ximon18]

Routinator 0.4+ now deploys but the playbook logic for obtaining the most recent Routinator serial number no longer works:

fatal: [routinator]: FAILED! => {"msg": "Unexpected templating type 
error occurred on ({{ result.stderr_lines | select('match', '^New serial is ([0-9]+)')
| list | last | regex_search('([0-9]+)', '\\\\1') | first }}): expected string or 
bytes-like object"}