tests/test-gendoc-el.t

cleanup: say goodbye to manifestv2 format

This experiment was a bust: we'd hoped for smaller repository sizes,
but things got larger. Google ended up rolling out tree manifests in a
format that's compatible with the original manifest format, and I
believe Facebook is doing the same. This code was never implemented as
native speedups, so I'm pretty comfortable saying nobody is using the
experimental feature. Let's rip it out.

I noticed this code still kicking around because I was investigating a
repo corruption issue for timeless.

.. bc::

   Support for the experimental manifestv2 format has been removed, as
   it was never completed and failed to meet expectations.

Differential Revision: https://phab.mercurial-scm.org/D2393

#require docutils gettext

  $ $TESTDIR/check-gendoc el
  checking for parse errors