R help - Jul 2016 - update of formula with conditional rhs introduces unwantedparentheses

Dear list members,

is anyone aware of a (simple) strategy to prevent update() from
introducing parentheses around a conditional rhs of a formula
when updating, e.g., only its lhs? Simple example:

update( y ~ a|b, log(.) ~ .)

gives log(y) ~ (a | b), but I want/need log(y) ~ a | b


I do know how to extract various components of a formula and how to
"re-build" formulae from such single components, but I would like to
avoid that.

  Thx for any hint  --  Gerrit

---------------------------------------------------------------------
Dr. Gerrit Eichner                   Mathematical Institute, Room 212
gerrit.eichner at math.uni-giessen.de   Justus-Liebig-University Giessen
Tel: +49-(0)641-99-32104          Arndtstr. 2, 35392 Giessen, Germany
Fax: +49-(0)641-99-32109            http://www.uni-giessen.de/eichner