changegroup: exclude submanifests from manifest progress The progress callback for manifests is cleared outside of _unpackmanifests(), which means it will remain in effect while pulling subdirectory manifests when using treemanifests. Since the total number of revisions used for the progress is the number of changesets, the total number of treemanifest revisions is usually larger than that. One effect of this is that the ETA is negative. It's hard to estimate the number of subdirectory revisions, so let's just exclude them from progress for now.