remove: use ctx.hasdir(f) instead of 'f in ctx.dirs()' This speeds up 'hg remove python/README' on the Firefox repo from 2.479s to 0.664s with lazily loaded treemanifests (which is not yet in core) and has no measurable effect on flat manifests.

largefiles: drop os.path.join() in subrepo archive override This is related to 41cd8171e58f, but not required for that to function correctly because 'prefix' always ends with '/', so os.path.join(prefix, _path) simply concatenates the strings. Take the opportunity to drop the os.path usage, and avoid confusion by using the same pattern as the overridden subrepo method.

archive: drop the leading '.' path component from the prefix (issue4634) Unix utilities like tar will happily prefix the files it packs with './', but annoyingly, Windows Explorer will not show these packed files when it opens the archive. Since there doesn't seem to be a point in including './' in the path names, just drop it. The default 'hg archive' prefix is the basename of the archive, so specifying '.' allows for that default to be disabled completely.