Fix unexpected req.relative_path() when calling CWTC.app_handle_request with path argument
The _deprecated_path_arg decorator can not be used in this case, since it won't
ensure backward compat if path value has been specified and is not similar as
req's path (which is generally the case).
This problem has been introduced by 904ee9cd0cf9.
### Requirements for tests in various cubicweb/**/test directories. ###
## shared by several test folders
cubicweb-card
docutils
Twisted < 16.0.0
webtest
## cubicweb/test
Pygments
mock
#fyzz XXX pip install fails
cubicweb-file
cubicweb-localperms
cubicweb-tag
## cubicweb/devtools/test
flake8
## cubicweb/hooks/test
psycopg2
## cubicweb/pyramid/test
pyramid >= 1.5.0
waitress >= 0.8.9
wsgicors >= 0.3
pyramid_multiauth
## cubicweb/sobject/test
cubicweb-comment