fix update from pre-1.46 to post-1.46 not working in docker

[SoongJr]

The script previously used [[ ! -f /.docker-image ]] && { ... } as its last statement, which returns non-zero in docker (as it should), but this exit code is then used as the over-all exit code of the update script, thus failing the update whenever used in docker container. Fixed by adding the same exit 0 that's already there in all other update-scripts. Fixes issue #1405

Also removed a quote that I'm pretty sure shouldn't be there.

[SoongJr]

One minor concern I have is that the addition of set -e means that for non-docker images, if any of the following commands fails, the update will now be considered failed where it would previously ignore if any of the first two fails:

  systemctl daemon-reload
  systemctl enable refresh_notify_push.{path,service}
  systemctl restart refresh_notify_push.path

This is a change in behavior, but I hope a desirable one. Previously only the systemctl restart would have caused the update to abort as it's the last statement in the script and its return code becomes the code of the whole script.
Not sure the other two commands can even fail to be honest, just adding this for full disclosure. A test with a non-docker image would definitely be a good idea, but I don't have one ;)

[svenb1234]

@nachoparker @theCalcaholic could you please review this commit? Or is this not the correct fix for the issue?

[nachoparker]

many thanks for this