tests/test-gendoc-el.t

dirstate: explicitly write the dirstate after `keyword` "overwrite"

I am working on making the dirstate write patterns more predictable. This patch is
part of a small series of similar patches that adds a explicit dirstate write in
a handful of location where the dirstate is updated "a bit in a strange way".

With this explicit write, we are no longer relying on implicite write of the
dirstate on `wlock` release. This make the world a better place.

#require docutils gettext

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