#68 getForm edge case

[Jean Jordaan]

On frmA we have a field formula that calls `somedoc.openWithForm(somedoc.getForm())`.
To our surprise somedoc is called with the wrong form (not with `somedoc.Form`).
But we're looking at http://.../23423432?openwithform=frmA

The problem is that `getForm` finds `openwithform` in the request, so in this case all `getForm` calls on `frmA` are going to return `frmA`.
This is clearly undesirable; no way all possible docs that we're working with should get one and the same form.