http authentication is disabled

When I try to publish to a Sonatype Nexus server, with <credentials/> fully populated, according to the Nexus debug logs, the header was empty, so it goes with anonymous. According to ant -debug, at the end of the deliver block:
Jan 31, 2013 9:41:36 AM org.apache.commons.httpclient.HttpMethodDirector isAuthenticationNeeded
INFO: Authentication requested but doAuthentication is disabled

Why is doAuthentication disabled? How can I enable it? I have all the 2.3.0 dependencies in the lib folder of the project, so it uses its commons-httpclient-3.0.jar rather then the jdk (which doesn't support http auth, apparently?)

Until I put commons-httpclient-3.0.jar into its lib/classpath folder, it wasn't even trying. Now it says requested but doAuthentication is disabled.