Obsolete and duplicate entries in classpath when moving to another Nuxeo version

Steps to reproduce :

• Using Nuxeo IDE, I create a Nuxeo plug in project using a 5.7.3 sdk
• I copy my project on another computer
• On this new computer, I install eclipse with a 5.8 sdk
• I import my project in eclipse
• As Nuxeo IDE cannot find the 5.7.3 dependencies it the sdk classpath, it adds it to the user libraries, creating duplicate jar entries

These entries are hard to detect since user libraries appear in the sdk classpath container.