The problem is related to non standard (i.e. "wicket") namespaces.
In my quickstart if I change the namespace in all markup from "wicket"
to "foobar" then the BPL which has only the last segment differing from the current page ends up producing an incorrect link to another page in the same path.
Browser is at this page:
Here's a relative link to another page in the same 'path'
<a foobar:id="janeLink" href="../../../../../jane"
A link to the current page
<a foobar:id="fredLink" href="fred">fred</a> </p>
The above BPL href of ../../../../../jane is wrong.
With 'wicket' set as the namespace the 'jane' BPL outputs 'jane' which is correct.
This same code worked with the non standard namespace under 1.4.x
Attached quickstart demonstrates the issue.