I'm not sure how sensitive vscode needs to be about file i/o. The bug here is that rebase detection was unaware that if the rebase directory is missing, there is no rebase in progress. I added a couple of async fs.exists calls parallel to the existing code that reads the rebase commit hash. If we think it is far more common that the user is not dealing with a rebase collision, we may want to optimize around that. We could wait until after successfully reading the hash before checking for the rebase directories. I believe that would make it slightly slower in the less common case in which a rebase is happening.

A completely different option would be to read the commit hash from one of the rebase folders and forego the REBASE_HEAD file.