tests/test-gendoc-ro.t

dirstate-tree: Add tree traversal/iteration

Like Python’s, Rust’s iterators are "external" in that they are driven
by a caller who calls a `next` method. This is as opposed to "internal"
iterators who drive themselves and call a callback for each item.

Writing an internal iterator traversing a tree is easy with recursion,
but internal iterators cannot rely on the call stack in that way,
they must save in an explicit object all state that they need to be
preserved across two `next` calls.

This algorithm uses a `Vec` as a stack that contains what would be
local variables on the call stack if we could use recursion.

Differential Revision: https://phab.mercurial-scm.org/D10370

#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.