[mod_python] Request object attribute "content_type" does not support UNICODE STRINGS

When I try to set content_type to a unicode string, it gives a TypeError saying that content_type can only be string. I don't know if this is correct. Although content types will not use any hich codes, in my case the content-type value I read it from an XML file that IS in Unicode, therefore I must convert it using str() which I dont like cause if I get anything there that is not really string (Unicode or Normal) python will anyway convert it.
Is this behaviour expected?