Comment 2 for bug 1691485

SRU Justification:

Impact: The function which does docker config updates/tests currently does not check for the presence of the docker command itself. And while there are error messages to stderr a call to check for fan being configured for docker accidentally results in returning true.

Fix: Adding a check for the docker command being present early in the function and return an error in that case (which is a false in the is-docker-configured case). Since the function should really always fail if there is no docker present the risk of regressions should be low.

Testcase:
 - [docker is not installed]
 - fanatic enable-fan ...
 - fanatic disable-fan ...