remotefilelog: prefetch files in deterministic order I have been troubleshooting some slowness in this area (it's unclear if it's the client or server that's to blame, but that's beside the point) and it's a lot easier to do troubleshoot if the files are prefetched in the same order each time. Differential Revision: https://phab.mercurial-scm.org/D6172

debugdiscovery: display time elapsed during the discovery step This is a useful information. Now that we perform more analysing after the discovery is done, it is worth have a more precise measurement. For serious timing analysis use `hg perfdiscovery`.