Ran into an interesting issue at work today. My pair (Dave) and I opened a pull request yesterday and I checked the status this morning. It showed that Dave had closed it this morning. I asked him if he had intended to merge it, and he said he hadn’t closed it.
The weird thing was that when looking at the pull request, reopening the pull request was not an option. I had not seen that before, so I started asking around.
So, long story short, it turns out that Dave was cleaning up his branches and accidentally deleted the branch that the pull request was based on. This caused Github to close the pull request because the branch it was based on no longer existed.
I fixed this by re-pushing the branch and refreshing the pull request page. At that point, I had the ability to re-open the pull request.