Major Description
With the PhantomJS browser form submit is done using get instead of post due to change [1] since 6.12.0
This is incorrect and fails with larger requests, PhantomJS only allows a limited get request size. For PhantomJS post must be used as for other browsers.
[1] https://git-wip-us.apache.org/repos/asf?p=wicket.git;a=commitdiff;h=f0b251e3