Nexus requires a Servlet 3.0 compliant container. It comes bundled with a Servlet 3.0 compliant Jetty 8. If you deploy it on another container you have to make sure it is compliant. Couldn't find this in the documtation but from own experience it seems to be the case.
When you
HTTP GET
http://xxx.xxx.com:8080/nexus/content/repositories/snapshots/com/xxx/utils/licm/0.2.9-SNAPSHOT/maven-metadata.xml
in a browser you should be able to see the stacktrace, which contains
java.lang.NoSuchMethodError: javax.servlet.http.HttpServletResponse.getStatus()
This is only available in Servlet 3.0 containers.