It seems that there still are problems with conf mappings containing
whitespace around semicolon separator. The rules for using semicolon are
supposedly self-evident and are not explained anywhere AFAICS.
My understanding is that semicolon is used in situtations when different
confs have different mappings, like "A->default;B->master" or "A;B->master"
when defaultconfmapping is set. I cannot find a specification, though, what
should happen when defaultconfmapping is not set or when conf is "A;B": an
exception or semicolon interpreted as comma?