tests/test-gendoc-ro.t

rhg: Add support for `rhg status --copies`

Copy sources are collected during `status()` rather than after the fact like
in Python, because `status()` takes a `&mut` exclusive reference to the dirstate map
(in order to potentially mutate it for directory mtimes) and returns `Cow<'_, HgPath>`
that borrow the dirstate map.

Even though with `Cow` only some shared borrows remain, the still extend the same
lifetime of the initial `&mut` so the dirstate map cannot be borrowed again
to access copy sources after the fact:

https://doc.rust-lang.org/nomicon/lifetime-mismatch.html#limits-of-lifetimes

Additionally, collecting copy sources during the dirstate tree traversal that
`status()` already does avoids the cost of another traversal or other lookups
(though I haven’t benchmarked that cost).

Differential Revision: https://phab.mercurial-scm.org/D11899

#require docutils gettext

Error: the current ro localization has some rst defects exposed by
moving pager to core. These two warnings about references are expected
until the localization is corrected.
  $ $TESTDIR/check-gendoc ro
  checking for parse errors
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.
  gendoc.txt:58: (WARNING/2) Inline interpreted text or phrase reference start-string without end-string.