Warning logged when navigating via facetselect to faceted navigation node with multiple docbases

When a faceted navigation node has multiple docbases (i.e. comma-separated list of UUIDs in the property hippo:docbase), and the node is retrieved via a facetselect, a warning is logged:

26.11.2010 15:13:45 WARN [org.hippoecm.repository.jackrabbit.ViewVirtualProvider.populate():69] invalid docbase 'bcf80aea-e0ad-42fe-8cdc-8849a7e20970,4744a96f-c56d-4e47-94fe-f6e07ef26227,71784119-70bf-4ceb-903f-01297a959127' because not a valid UUID

This warning pollutes the logs.

Steps to reproduce:
1. create a hippofacnav with multiple docbases, for example this node in /content/documents:

<sv:node sv:name="searchfacets" xmlns:sv="http://www.jcp.org/jcr/sv/1.0">
<sv:property sv:name="jcr:primaryType" sv:type="Name">
<sv:value>hippofacnav:facetnavigation</sv:value>
</sv:property>
<sv:property sv:name="hippo:docbase" sv:type="String">
<sv:value>bcf80aea-e0ad-42fe-8cdc-8849a7e20970,4744a96f-c56d-4e47-94fe-f6e07ef26227,71784119-70bf-4ceb-903f-01297a959127</sv:value>
</sv:property>
<sv:property sv:name="hippofacnav:facetnodenames" sv:type="String">
<sv:value>documenttype</sv:value>
</sv:property>
<sv:property sv:name="hippofacnav:facets" sv:type="String">
<sv:value>jcr:primaryType</sv:value>
</sv:property>
</sv:node>

2. browse to this facet via a facetselect, for example by opening http://localhost:8080/cms/repository/live/rvr/hst:content/searchfacets

Expected behavior: no warnings are logged
Actual behavior: a warning is logged about the hippo:docbase value not being a valid UUID

BTW: the faceted navigation itself seems to work just fine, using documents in all specified docbases.