[tex4ht] [bug #482] Can't load fonts with polyglossia

[Karl Berry]

    I see. I guess that there is a missing \endgroup somewhere? I think
    this can be quite hard to find :/

Running with etex and \loggingall (specifically \tracinggroups=1, as I
recall), the log file will continue with a line like

### simple group (level 1) entered at line 1 ({)

Unfortunately it does not report the file (Phelype is contemplating
working on that), but at least it would be a glimmer of a clue ... -k