ngx.var: added a (passing) test for writing to a non-changeable nginx variable.
ngx.var: added a (passing) test for writing to a non-changeable nginx variable.

yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx,yeahdongcn/SEnginx