Speed up hg grep by avoiding useless manifest parsing In the kernel repo (tip = 2b89f7111b96), a "hg grep mpm MAINTAINERS" goes from ~165s to 0.7s. This could get even a bit faster if we broke out of the loop after the first match, but I'm not sure how that would interact with the --follow code. This is obviously an extreme example, but other cases should also benefit from this patch.