[Groff] Forcing a blank page

[Timothy Groves]

.bp works fine for forcing a new page.  But what I'd like to do is to 
force a blank page based on the page number.  When I try:

.bp
.if o .bp
it doesn't work reliably.  Sticking in a non-breaking space will force 
the results, but it will also insert an undesired blank line if the 
forced break is not needed.  Is there a reliable way to handle this?