Here is a scenario that looks like a defect in bitbucket.
Have 2 branches in bitbucket repo
1. develop 2. release
One commit that was present in develop branch, i used the git cherry pick command to push to release branch. Once that is done, the same commit is now present in release and develop both.
Even after this, if i raise a pull request from develop to release the same commit still shows up in the differences.
I think this is a defect on bitbucket side, and should be fixed. Happy to hear what others think about this.