When validating a publication, remove existing proxies in a unrestricted session

Caused by: org.nuxeo.ecm.platform.publisher.api.PublishingException: Privilege 'ReadVersion' is not granted to 'validateur'
	at org.nuxeo.ecm.platform.publisher.task.CoreProxyWithWorkflowFactory.removeExistingProxiesOnPreviousVersions(CoreProxyWithWorkflowFactory.java:214)
	at org.nuxeo.ecm.platform.rendition.publisher.RenditionPublicationFactory.removeExistingProxiesOnPreviousVersions(RenditionPublicationFactory.java:101)
	at org.nuxeo.ecm.platform.publisher.task.CoreProxyWithWorkflowFactory.validatorPublishDocument(CoreProxyWithWorkflowFactory.java:224)
	at org.nuxeo.ecm.platform.publisher.api.AbstractBasePublicationTree.validatorPublishDocument(AbstractBasePublicationTree.java:175)
	at org.nuxeo.ecm.platform.publisher.impl.service.PublisherServiceImpl.validatorPublishDocument(PublisherServiceImpl.java:603)
	at org.nuxeo.ecm.platform.publisher.impl.service.AbstractRemotableTree.validatorPublishDocument(AbstractRemotableTree.java:137)
	at org.nuxeo.ecm.platform.publisher.web.PublishActionsBean.approveDocument(PublishActionsBean.java:489)
Caused by: org.nuxeo.ecm.core.api.DocumentSecurityException: Privilege 'ReadVersion' is not granted to 'validateur'
	at org.nuxeo.ecm.core.api.AbstractSession.checkPermission(AbstractSession.java:203)
	at org.nuxeo.ecm.core.api.AbstractSession.getSourceDocument(AbstractSession.java:1758)
	at org.nuxeo.ecm.platform.publisher.task.CoreProxyWithWorkflowFactory.removeExistingProxiesOnPreviousVersions(CoreProxyWithWorkflowFactory.java:198)
	... 124 more