Extender controls may not be registered before PreRender when using form picker

Questions
1

I just installed 1.1.13.2

I get a "Extender controls may not be registered before PreRender"

error when rendereing the form from a form picker.

If i insert the form in the RTE, it renders fine.
If i insert the form in the RTE, the form selected by the form picker renders fine...

When inspecting the page source i find, that the form inserted in the RTE is prceded by a script

<script type="text/javascript">
//<![CDATA[
Sys.WebForms.PageRequestManager._initialize('ctl00$ctl00$ctl00$ContentPlaceHolderDefault$CphMain$ctl02$RenderForm_6$ctl00', 'RunwayMasterForm', [], [], [], 90, 'ctl00$ctl00$ctl00');
//]]>
</script>

This script is not present when the form is inserted via the form picker...

This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/34206-extender-controls-may-not-be-registered-before-prerender-when-using-form-picker