tests/test-gendoc.t

zsh_completion: install as _hg not hg

The contrib/zsh_completion file itself says to name it _hg.

With a name like `hg`, if the user has a line like `autoload ${^fpath}/*(N-.:t)`
in their zshrc, it will create a shell function named `hg` that will hide the
actual hg command and make hg unusable.

Separately from that though, the underscore prefix makes it actually work. The
zsh man page states:

    The convention for autoloaded functions used in completion is that they
    start with an underscore

This does not seem to just be a "convention", though. With the ill-advised line
removed from my zshrc and the file named
`/usr/local/share/zsh/site-functions/hg` (without the underscore), these
completions did not seem to get loaded and the ones from the zsh installation
were loaded instead.  If I renamed them to be
`/usr/local/share/zsh/site-functions/_hg`, however, they were loaded.

I manually tested the above statement by starting a new zsh instance with the
file in `/usr/local/share/zsh/site-functions` with the following names:
- As `hg`, `which _hg_labels` did not show anything
- As `_hg`, `which _hg_labels` showed the expected function.

#require docutils
#require gettext

Test document extraction

  $ HGENCODING=UTF-8
  $ export HGENCODING
  $ { echo C; ls "$TESTDIR/../i18n"/*.po | sort; } | while read PO; do
  >     LOCALE=`basename "$PO" .po`
  >     echo "% extracting documentation from $LOCALE"
  >     LANGUAGE=$LOCALE python "$TESTDIR/../doc/gendoc.py" >> gendoc-$LOCALE.txt 2> /dev/null || exit
  > 
  >     if [ $LOCALE != C ]; then
  >         if [ ! -f $TESTDIR/test-gendoc-$LOCALE.t ]; then
  >             echo missing test-gendoc-$LOCALE.t
  >         fi
  >         cmp -s gendoc-C.txt gendoc-$LOCALE.txt && echo "** NOTHING TRANSLATED ($LOCALE) **"
  >     fi
  > done; true
  % extracting documentation from C
  % extracting documentation from da
  % extracting documentation from de
  % extracting documentation from el
  % extracting documentation from fr
  % extracting documentation from it
  % extracting documentation from ja
  % extracting documentation from pt_BR
  % extracting documentation from ro
  % extracting documentation from ru
  % extracting documentation from sv
  % extracting documentation from zh_CN
  % extracting documentation from zh_TW