form: add novalidate to cancel, previous and save-draft buttons (#6188)

wcs/qommon/form.py

@@ -178,6 +178,13 @@ def text_render_content(self):
 TextWidget.render_content = text_render_content
 
 
+def submit_render_content(self):
+    if self.name in ('cancel', 'previous', 'save-draft'):
+        self.attrs['formnovalidate'] = 'formnovalidate'
+    return super(self.__class__, self).render_content()
+SubmitWidget.render_content = submit_render_content
+
+
 def radiobuttons_render_content(self):
     tags = []
     for object, description, key in self.options: