As of the parent commit, there is a generic "may_fail" option through
which we could still ignore an error. Thus, command_fail is superfluous,
and avoids some extra code.
Further, in all these cases, we should better be informed about any
error, so let's not use may_fail for these tests.
There might be various occasions where a CI step should be attempted to
be executed, despite a chance of failing. For instance, we might want
to try executing an instable Iperf test, and still mark the CI as
passing if it fails.
This commit introduces a generic "may_fail" option that will mark any CI
test as succeeded, despite having failed.
Ideally, we would print a warning in the HTML code, but this is not
possible because each step emits its own HTML code, instead of the main
loop handling this. We can improve this in the future.
Use the previous commit on returning success from each task execution
function, and implement handling of errors in the main loop. Add a
script with which this is visible using Custom_Commands.