[Xy-pic] double-framed round node yields bad PDF

[Ben Liblit]

The following test input should produce two Xy-pic diagrams, each
containing a single double-framed round node:

	\documentclass{article}
	\usepackage[frame,matrix]{xy}
	\begin{document}
	  \xymatrix{*+[o][F=]{}}
	  \xymatrix{*+[o][F=]{}}
	\end{document}

I render this directly to PDF using pdflatex version 3.1415926-1.40.11
(TeX Live 2011/dev) with Xy-pic version 3.8.2 <2010/06/17>.  When I view
the PDF result in Adobe Acrobat Reader 9.4 under Linux, neither node
appears.  Instead, Reader shows an error dialog reading "An error exists
on this page.  Acrobat may not display the page correctly.  Please
contact the person who created the PDF document to correct the problem."

Evince 2.30.3 is able to show the PDF document, including the two nodes,
but produces the following console output:

	Error (309): Unknown operator 'hh'
	Error (323): Unknown operator 'hh'
	Error (309): Unknown operator 'hh'
	Error (323): Unknown operator 'hh'
	Error (309): Unknown operator 'hh'
	Error (323): Unknown operator 'hh'
	Error (309): Unknown operator 'hh'
	Error (323): Unknown operator 'hh'

Weirdly, if I remove one of the two Xy-pic diagrams, then Acrobat Reader
does not present an error dialog, but it still fails to draw the (one)
double-framed round node.

I have also tried building this document using pdflatex version
3.1415926-1.40.9 (Web2C 7.5.7) with Xy-pic version 3.7 <1999/02/16>.
The PDF document that this produces works fine, no errors, under both
Acrobat Reader and Evince.