copies: print debug information about copies per side/branch
Differential Revision: https://phab.mercurial-scm.org/D7987
== New Features ==
== New Experimental Features ==
== Bug Fixes ==
== Backwards Compatibility Changes ==
== Internal API Changes ==
* The deprecated `ui.progress()` has now been deleted. Please use
`ui.makeprogress()` instead.
* `hg.merge()` has lost its `abort` argument. Please call
`hg.abortmerge()` directly instead.
* The `*others` argument of `cmdutil.check_incompatible_arguments()`
changed from being varargs argument to being a single collection.