Thanks for the feedback.
Can you tell us what server you are using and what you did (code changing or server conf you added in order for rc to work) to let us know ? Maybe there is some code to change or a doc to write for this particular server ?
I'm using the latest git snapshot of uwsgi with its PHP plugin, there are no code changes in RC required, the bug was in uwsgi and has been fixed yesterday. I've attached a minimal, commented uwsgi configuration (intended for running as an uwsgi vassal behind a reverse proxy such as nginx) that should serve RC without any additional changes to Roundcube, it even emulates the .htaccess access controls and rewrites.