preventing gerrit changes from being merged

Hi,

recently some gerrit changes were accidentally merged into master  
through gerrit UI.
While there are ways to prevent it, like voting -2 for a change or  
prefixing the
commit message with "work in progress, please don't merge" or  
something like that,
I want to share with you the gerrit way to achieve that: draft queue feature.

Default queue in gerrit is publish queue. All changes are submitted to  
it per default.
Recently draft queue was introduced in gerrit. If you submit a change  
to draft queue it
cannot be merged. That change must be first promoted to publish queue.

To use draft queue, all you need is to pass -D switch to git-review:
git-review -D
If you don't use git-review, you can specify the draft queue on command line:
git push logerrit master:refs/draft/master
(or whatever branch you need).

When you are ready you can promote your change to publish queue with  
UI or with command line:
ssh logerrit gerrit review --publish <COMMIT | CHANGEID>

See https://gerrit.libreoffice.org/Documentation/cmd-review.html for  
more details.

Ciao
David