Set fonts to DejaVu to avoid the following error:
! Package polyglossia Error: The current latin font does not
contain the "Cyrillic" script!
This choice of font is consistent with the Russian intro and
tutorial manuals.
\language_package default
\inputencoding utf8
\fontencoding auto
-\font_roman "default" "default"
-\font_sans "default" "default"
-\font_typewriter "default" "default"
+\font_roman "default" "DejaVu Serif"
+\font_sans "default" "DejaVu Sans"
+\font_typewriter "default" "DejaVu Sans Mono"
\font_math "auto" "auto"
\font_default_family default
\use_non_tex_fonts false