[XeTeX] Fonts in running heads

[Vadim Radionov]

Dear all,

I once again have a problem with fonts in running heads, but the
previous recipe doesn't work now. Can you clarify for me what's
happening?  With \setdefaultlanguage{russian} the footer on the first
page is set in sans-serif font (which is active when the page is being
output) while without it both footers are set in main font (and the
russian word is not hyphenated, of course).

Thank you in advance,

Vadim

===========
\documentclass{book}

\usepackage{geometry}
\geometry{lines=2,papersize={3in,2in},width=1.71in}

\usepackage{polyglossia}

\setdefaultlanguage{russian}

\setmainfont[Script=Cyrillic]{Linux Libertine O}
\setsansfont[Script=Cyrillic]{Linux Biolinum O}

\pagestyle{plain}
\begin{document}
2 Libetine. Либертин.

{\sffamily
1 Biolinum. Biolinum.  Биолинум.

1 Biolinum. Биолинум.

}

\end{document}