tests/test-gendoc-zh_CN.t

branchmap: Add a test about writing branchmap and aborted transaction

It turn out that we update the branchmap on disk whenever we recompute it…
including in a middle of a transaction. This means writing the new branchmap too
early (the changeset are not visible yet) and worse… it mean writing branchmap
for transaction we rollback.

so we introduce a test to highlight the issue (and prevent it to regress in the
future).

Differential Revision: https://phab.mercurial-scm.org/D12126

#require docutils gettext

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