Setting <display-facets>false</display-facets> throws InvalidQNameException

Customer was configuring Share and faceted search and reported this issue.

In Ent5.0.1, adding the following configuration to shared/alfresco/web-extension/share-config.custom.xml throws an exception "org.alfresco.service.namespace.InvalidQNameException: A QName must consist of a local name" . Exception doesn't occur in Ent 5.0.0.7.

<config evaluator="string-compare" condition="Search" replace="true">
<search>
<display-facets>false</display-facets>
</search>
</config>

Steps to reproduce:
1) Add the above evaluator to share-config-custom.xml
2) Restart Alfresco
3) Search for something.

Full stack trace:
2015-05-04 10:05:45,544 ERROR [solr.core.SolrCore] [http-bio-8443-exec-5] org.alfresco.service.namespace.InvalidQNameException: A QName must consist of a local name
at org.alfresco.service.namespace.QName.createQName(QName.java:67)
at org.alfresco.repo.search.impl.parsers.AlfrescoFunctionEvaluationContext.getLuceneFieldName(AlfrescoFunctionEvaluationContext.java:377)
at org.alfresco.solr.AlfrescoSolr4FunctionEvaluationContext.getLuceneFieldName(AlfrescoSolr4FunctionEvaluationContext.java:59)
at org.alfresco.solr.AlfrescoSolrDataModel.mapProperty(AlfrescoSolrDataModel.java:2132)
at org.alfresco.solr.component.RewriteFacetParametersComponent.rewriteFacetFieldList(RewriteFacetParametersComponent.java:176)
at org.alfresco.solr.component.RewriteFacetParametersComponent.fixFacetParams(RewriteFacetParametersComponent.java:75)
at org.alfresco.solr.component.RewriteFacetParametersComponent.prepare(RewriteFacetParametersComponent.java:53)
at org.apache.solr.handler.component.AlfrescoSearchHandler.handleRequestBody(AlfrescoSearchHandler.java:233)
at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:135)
at org.apache.solr.core.SolrCore.execute(SolrCore.java:1962)
at org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:777)
at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:418)
at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:207)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:613)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1074)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)