Comment 1 for bug 303973

Thank you for taking the time to report this bug and helping to make Ubuntu better.
/etc/fonts/conf.d/49-sansserif.conf from Lucid seems to not have this problem , the bug seems to have been fixed a while ago. Closing bug report as fixed.

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!--
  If the font still has no generic name, add sans-serif
 -->
 <match target="pattern">
  <test qual="all" name="family" compare="not_eq">
   <string>sans-serif</string>
  </test>
  <test qual="all" name="family" compare="not_eq">
   <string>serif</string>
  </test>
  <test qual="all" name="family" compare="not_eq">
   <string>monospace</string>
  </test>
  <edit name="family" mode="append_last">
   <string>sans-serif</string>
  </edit>
 </match>
</fontconfig>