copies: introduce a basic Rust function for `combine_changeset_copies` This new function mirror the python code. This first implementation does a lot of data copies and is therefore quite slow. However my goal here is to create a simple "frame" from where to start adding optimization. This patch focus on the `hg-core` part of this work. Coming patches will do the necessary `hg-cpython` work to be able to use this from Python. Differential Revision: https://phab.mercurial-scm.org/D9297

--- a/rust/hg-core/src/lib.rs	Fri Nov 27 17:11:56 2020 -0500
+++ b/rust/hg-core/src/lib.rs	Thu Oct 01 18:51:06 2020 +0200
@@ -20,6 +20,7 @@
     CopyMap, CopyMapIter, DirstateEntry, DirstateParents, EntryState,
     StateMap, StateMapIter,
 };
+pub mod copy_tracing;
 mod filepatterns;
 pub mod matchers;
 pub mod revlog;