Upstream: ngx_http_upstream_store() error handling fixes. Previously, ngx_http_map_uri_to_path() errors were not checked in ngx_http_upstream_store(). Moreover, in case of errors temporary files were not deleted, as u->store was set to 0, preventing cleanup code in ngx_http_upstream_finalize_request() from removing them. With this patch, u->store is set to 0 only if there were no errors. Reported by Feng Gu.