CH2 SA endpoint doesn't support slice lookup

Or at least, it doesn't seem to. If you try to lookup slices by project, you get:

<?xml version="1.0"?>
<methodResponse>
<params>
<param><value><struct>
<member><name>protogeni_error_log</name><value><string>urn:publicid:IDN+emulab.net+log+707469b2bfc267e65edecc38ae666951</string></value></member>
<member><name>protogeni_error_url</name><value><string>https://www.emulab.net/spewlogfile.php3?logfile=707469b2bfc267e65edecc38ae666951</string></value></member>
<member><name>value</name><value><i4>0</i4></value></member>
<member><name>output</name><value><string>lookup SLICE does not implement match &quot;SLICE_PROJECT_URN&quot;</string></value></member>
<member><name>code</name><value><i4>1</i4></value></member>
</struct></value>
</param>
</params>
</methodResponse>

(this is the non-sub-SA endpoint, so I would expect to have to tell it what project I am looking for)