Please let me know if there is a better way to do this. This is the workaround I found.
list of remote branches
git branch -va
check PR branch
git checkout origin pr_branch
overwrite pr_branch file with other_branch file
git checkout other_branch -- ./path/to/file
commit changes
git commit -m "overwrite with other_branch's"
push your changes
git push origin pr_branch
source share