When opening a Draft Pull Request the world driven message is commented with a time to merge.
This message should only happen on non Draft Pull Request creation, or changing the status from Draft to Open.

it just came to my mind that we should add an extra toggle box for enable add ?w=1 at the url for diff page when a MR contains lots of whitespace diff which might be annoying and redundant for a user to review the core code logic.
Ref: https://gitlab.com/gitlab-org/gitlab-ce/issues/1393