Good catch. It's possible that Google doesn't allow ; as separator.
In that case, parameterize form-urlencoded-separator to "&;" or just "&".
This parameter is for uri-common, which defaults to ";&" because
of the recommendation in the HTML spec to prefer ";" as separator, but
to also allow "&" on input. The reason is the former doesn't have to be
specially encoded in HTML.
"The process of preparing programs for a digital computer
is especially attractive, not only because it can be economically
and scientifically rewarding, but also because it can be an aesthetic
experience much like composing poetry or music."
-- Donald Knuth