Link walk url test failing on CentOS 6

This has only been seen in one box, one run so far. We are getting a 500:
19:41:23.704 [info] Verifying ("a","1") '_,next,1/b,next,1/_,next,1/_,next,1/_,next,1' -> ["v2"]
19:41:24.006 [error] Error in process <0.13011.0> on node 'riak_test@127.0.0.1' with exit value: {{badmatch,{ok,"500",[{"Server","MochiWeb/1.1 WebMachine/1.9.2 (someone had painted it blue)"},{"Expires","Tue, 08 Jan 2013 00:51:23 GMT"},{"Date","Tue, 08 Jan 2013 00:41:24 GMT"},{"Content-Type","text/html"},{"Content-Len...