remotefilelog: import pruned-down remotefilelog extension from hg-experimental This is remotefilelog as of my recent patches for compatibility with current tip of hg, minus support for old versions of Mercurial and some FB-specific features like their treemanifest extension and fetching linkrev data from a patched phabricator. The file extutil.py moved from hgext3rd to remotefilelog. This is not yet ready to be landed, consider it a preview for now. Planned changes include: * replace lz4 with zstd * rename some capabilities, requirements and wireproto commands to mark them as experimental * consolidate bits of shallowutil with related functions (eg readfile) I'm certainly open to other (small) changes, but my rough mission is to land this largely as-is so we can use it as a model of the functionality we need going forward for lazy-fetching of file contents from a server. # no-check-commit because of a few foo_bar functions Differential Revision: https://phab.mercurial-scm.org/D4782

--- a/setup.py	Wed Oct 17 17:42:32 2018 +0300
+++ b/setup.py	Thu Sep 27 13:03:19 2018 -0400
@@ -844,6 +844,7 @@
             'hgext.infinitepush',
             'hgext.highlight',
             'hgext.largefiles', 'hgext.lfs', 'hgext.narrow',
+            'hgext.remotefilelog',
             'hgext.zeroconf', 'hgext3rd',
             'hgdemandimport']
 if sys.version_info[0] == 2: