title: Does Bitbucket and GitHub have Work In Progress [WIP] pull requests feature?
body: <p>I know there is a <a href="https://about.gitlab.com/2016/01/08/feature-highlight-wip/" rel="noreferrer">Work In Progress</a> (WIP) merge requests feature on GitLab. 
  I find it very useful when you already want to show the code to your peers and want to prevent 'Accept' button to be pressed. Is there a similar feature on Bitbucket? Tried to use <code>[WIP]</code> prefix on Pull Request name in Bitbucket, but it did not work out. </p>
  
  <p>I am also curious if GitHub has a similar feature too or you still need a <a href="https://github.com/sanemat/do-not-merge-wip-for-github" rel="noreferrer">plugin</a> for your browser?</p>