Add space as suffix in restructuredtext's section-numbering directive for epub output

Question

How do I add a space in reStructuredText's section-numbering directive, like such:

.. section-numbering:
  :suffix: 

This then is run through rst2epub. The result for html output is   but in epub format, this gets eaten and the section number jams.

if I put just typed spaces, I get this in the epub:

System Message: ERROR/3 (  <string>  , line 9) 
Error in "section-numbering" directive: invalid option value: (option: "suffix"; value: None) argument required but none supplied. 
.. section-numbering::
    :suffix:

If I put   then I get this in the epub

1.1 About this document

In the source code, the leading ampersand is replaced by &

Any clues? I'm willing to try any values you people come up with and report on it.

I am using FBreader on windows, but the target is Aldiko on Android.