Merge of r4471: Variables: honor no_cacheable for not_found variables. Variables with the "not_found" flag set follow the same rules as ones with the "valid" flag set. Make sure ngx_http_get_flushed_variable() will flush non-cacheable variables with the "not_found" flag set. This fixes at least one known problem with $args not available in a subrequest (with args) when there were no args in the main request and $args variable was queried in the main request (reported by Laurence Rowe aka elro on irc). Also this eliminates unneeded call to ngx_http_get_indexed_variable() in cacheable case (as it will return cached value anyway).