pull failing due to deleted .buildinfo files

I just tried to pull into my tree, and encountered several failures of this kind: == libraries/process: running git pull --rebase Cannot pull with rebase: You have unstaged changes. Please commit or stash them. But I have made no local changes, at least not on purpose. Git reports that: # Changes not staged for commit: # deleted: process.buildinfo I know how to revert this and keep going, but it seems that the build shouldn't be deleting files in the repo. Anyone know anything about this? Cheers, Simon