No creation of issues/comment by e-mails with no text/plain, but only html version of the content

E-mails with no text/plain but only a html version of the content are not processed by Create Issue / Comment Handler.

We have many customers, who are accustomed to open calls by emails using any e-mail client in any configuration. So we have no control, that everyone configure his e-mail client to send the content also as text/plain.