media-fonts/roboto/files/90-roboto-regular.conf

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>

	<match target="pattern">
		<test name="family" compare="eq"><string>Roboto</string></test>
		<edit name="weight" mode="append"><const>regular</const></edit>
	</match>
	<match target="pattern">
		<test name="family" compare="eq"><string>Roboto Condensed</string></test>
		<edit name="weight" mode="append"><const>regular</const></edit>
	</match>

</fontconfig>