Fix behavior on nginx

From separate internal investigation (internal ref: DP-437290):

The Git Source Control module uses a CGI variable of REQUEST_URI during URL parsing / construction.

Relevant code in webuidriver.csp:
`Set url = $Piece($Get(%request.CgiEnvs("REQUEST_URI"),$Get(%request.CgiEnvs("HTTP_URL"))),"?")`

However, traffic from the Nginx web gateway does not come with this variable and causes "Set url" to an empty string and the malformed URL mentioned in the customer's description. (i.e. this variable is good with Apache, not Nginx).

For a workaround for Nginx users, adding this line of code right after the above one fixes the issue.
`Set:(url="") url = %request.URL _ %request.CgiEnvs("PATH_INFO")`