extensions: load help from hgext.__index__ as a fallback this time
Prior to 843418dc0b1b, `hgext.__index__` was consulted first if present, which
caused the longer help from the extension modules to be ignored, even when
available. But that change causes a bunch of test failures when the pyoxidized
binary bundles *.pyc in the binary, saying the there's no help topic for
`hg help $disabled_extension` and suggesting the use of `--keyword`, rather than
showing a summary and indicating that it is disabled. Current failures were in
test-check-help.t, test-extension.t, test-help.t, and test-qrecord.t.
Ideally, we would read the various *.pyc files from memory and slurp in the
docstring, but I know that they used to not be readable as resources, and I
can't figure out how to make it work now. So maybe 3.9 and/or the current
PyOxidizer doesn't support it yet. I got closer in py2exe with
`importlib.resources.open_binary("hgext", "rebase.pyc")`, but `open_binary()` on
*.pyc fails in pyoxidizer.[1] Either way, the *.pyc can't be passed to
`ast.parse()` as `extensions._disabledcmdtable()` is doing, so I'm setting that
aside for now.
[1] https://github.com/indygreg/PyOxidizer/issues/649
#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