Reviving pull requests
It is not uncommon that a pull request is more or less finished, but then there are some minor details left that the author for various reasons will not complete, even after waiting for quite some time.
There is the process of Closing pull requests, but there is also a need to finish these simple-to-finish abandoned pull requests. Hence, there is also an option to mark a closeable pull request "easy to revive". This means that anyone should feel free to finish the final details and resubmit it. It is important that a revived pull request is based on the previous so that all commit messages etc are inherited and that one just do not simply copy and paste the code.
At the end of each pull request, in the box where the status of the checks are presented, there is a link called "command line instructions". Once clicked, there are two sections, one for checking out the pull request and one for merging the result. Here, only the first one should be applied.
First, it makes sense to make sure that you local master is up-to-date with the current master. This is done by
git pull origin master
where origin may be different depending on how you set up your local repository.
So, to revive a pull request, perform the commands listed under "Step 1: From your project repository, check out a new branch and test the changes." Typically this will be something like
git checkout -b new_branch_name master
git pull https://github.com/username/sympy.git branch_name
Now, normally it makes sense to merge with the current master, especially if the pull request states that there are conflicts. Make sure that you have updated to the latest master first, see above. Merging is done by
git merge master
If there are conflicts, resolve them and follow the instructions from git merge.
Perform the required changes and commit, push and create a pull request as usual.
In the description, please make sure that you mention the earlier pull request. Apart from that, write the information just as a normal pull request. Once merged, please close the revived pull request and add a comment stating that it was revived in another pull request and point to that pull request.
When marking a pull request for revival, make sure that the guidelines for Closing pull requests has been followed. Summarize what is required and choose the "Easy to revive" label.