[etwist] Fix an empty request content after a Twisted processing (closes #3546795).
The content of a POST request could be empty when the Twisted server is used.
[system]
db-driver = postgres
db-host = localhost
db-port = 5433
adapter = native
db-name = cw_fti_test
db-encoding = UTF-8
db-user = syt
db-password = syt
[admin]
login = admin
password = gingkow