1.32s$ sudo service postgresql stop
* Stopping PostgreSQL 9.1 database server * Stopping PostgreSQL 9.2 database server * Stopping PostgreSQL 9.3 database server * Stopping PostgreSQL 9.4 database server
cp: cannot stat `/var/lib/postgresql/9.6': No such file or directory
0.05s$ sudo service postgresql start 9.6
PostgreSQL 9.6 is not installed!
...and it looks like they have been for a while.
See https://travis-ci.org/PyconUK/ironcage/builds/250375431 for instance.
Looks like this is the cause: