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

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-remotefilelog-blame.t	Thu Sep 27 13:03:19 2018 -0400
@@ -0,0 +1,33 @@
+  $ PYTHONPATH=$TESTDIR/..:$PYTHONPATH
+  $ export PYTHONPATH
+
+  $ . "$TESTDIR/remotefilelog-library.sh"
+
+  $ hginit master
+  $ cd master
+  $ cat >> .hg/hgrc <<EOF
+  > [remotefilelog]
+  > server=True
+  > EOF
+  $ echo x > x
+  $ hg commit -qAm x
+  $ echo y >> x
+  $ hg commit -qAm y
+  $ echo z >> x
+  $ hg commit -qAm z
+  $ echo a > a
+  $ hg commit -qAm a
+
+  $ cd ..
+
+  $ hgcloneshallow ssh://user@dummy/master shallow -q
+  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
+  $ cd shallow
+
+Test blame
+
+  $ hg blame x
+  0: x
+  1: y
+  2: z
+  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)