How to reproduce:

• Use an user that has a right on the root CMS context '/application'
• Check a rights on context '/contributor'. In the CMS, the right context prefix extension point will add '/application' to the prefix.
• The right manager will test the right on context '/application/contributor' and will return false (OK). Then it will test the right on the context '/application/' instead of '/application', hence it return false again.

This can be tested with the HasRightAction and StaticClientSideElement.
There are issues with two methods :

• hasRight (see how to reproduce above)
• hasRightOnContextPrefix (it does not work too, even if the cause are a bit different than in the previous case).