Binary package hint: fontconfig
I'm writing this bug as a consequence of bug 264254 comment 17.
Some background: Debian/Ubuntu have from some time patched Cairo with a patch from David Turner in order to use the lcd filtering algorithms from Freetype, which looks better for some people and configurations.
That patch has been merged to upstream recently (http://bugs.freedesktop.org/show_bug.cgi?id=10301) and Debian patch has been removed. However, there is a change between the old Debian patch and the upstream Cairo merge: the default lcd filter used by Debian was lcddefault, while the default one in Cairo is lcdlegacy (this is done in order to keep the same behavior as before).
In order to prevent the regression, I propose to include a configuration file in Ubuntu's Fontconfig which sets the lcd filter to lcddefault. That should be similar to the 10-autohint.conf configuration file, but with configuration:
<match target="font">
<edit mode="assign" name="lcdfilter">
<const>lcddefault</const>
</edit>
</match>
Here is the debdiff.