cubicweb #4191812 WSGI handler ignore CONTENT_TYPE [validation pending]

With the current implementation only the HTTP_CONTENT_TYPE can set the content type, but the wsgi spec have a CONTENT_TYPE for that which is more recommended.

See http://legacy.python.org/dev/peps/pep-0333/#environ-variables

prioritynormal
typebug
done in3.19.4
load left0.000
closed by#46a8ed48636f [wsgi] Honor the 'CONTENT_TYPE' wsgi variable
patch[wsgi] Honnor the 'CONTENT_TYPE' wsgi variable [applied]