If PATH_INFO is "/", the percent encoded path info is also "/". No need for complex computation.

Note this fixes an issue with libfcgi app not hosted as root url such as "/sub/app.fcgi" on (old) IIS server.

library/server/wsf/src/wsf_request.e

@@ -841,6 +841,8 @@ feature -- Access: CGI meta parameters - 1.1
 				pi := path_info
 				if pi.is_empty then
 					l_result := ""
+				elseif pi.count = 1 and then pi[1] = '/' then
+					l_result := "/"					
 				else
 					r := request_uri
 					i := r.index_of ('?', 1)