cubicweb-bootstrap #3800619 <legend> tag is only authorized as the first child of a fieldset [validation pending]

Thus EntityFormRenderer.open_form monkey patch should be removed.

prioritynormal
typebug
done in0.6.4
load0.200
load left0.000
closed by#72b74fd6e286 [formrenderers] Stop using <legend> outside of <fieldset> (closes #3800619)
patch[forms] Replace EntityFormRenderer open_form and close_form monkey patches by CSS. [folded][formrenderers] Stop using <legend> outside of <fieldset> (closes #3800619) [applied]