tests/test-gendoc-da.t

exchange: use v2 bundles for modern compression engines (issue5506)

Previously, `hg bundle zstd` on a non-generaldelta repo would
attempt to use a v1 bundle. This would fail because zstd is not
supported on v1 bundles.

This patch changes the behavior to automatically use a v2 bundle
when the user explicitly requests a bundlespec that is a compression
engine not supported on v1. If the bundlespec is <engine>-v1, it is
still explicitly rejected because that request cannot be fulfilled.

#require docutils gettext

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