I can't test it with 12.0.1, since I can't get the update, but it
installed in TB 12.0. Here is the code from my altered install.rdf.
<!-- Thunderbird -->
<em:targetApplication>
<Description>
<em:id>{3550f703-e582-4d05-9a08-453d09bdfdc6}</em:id>
<em:minVersion>5.0</em:minVersion>
<em:maxVersion>12.0.*</em:maxVersion>
</Description>
</em:targetApplication>
There is also a Firefox and SeaMonkey section, so make sure you changed
the Thunderbird section.
--
Thunderbird (15.0a1) Daily | openSUSE 12.1 | KDE 4.7.2
Some people just have to pass on the right, when you are supposed to
pass on the left. Depending on the country.