Sub filter: restored ngx_http_set_ctx() at the proper place. Previously, ngx_http_sub_header_filter() could fail with a partially initialized context, later accessed in ngx_http_sub_body_filter() if called from the perl content handler. The issue had appeared in 2c045e5b8291 (1.9.4). A better fix would be to handle ngx_http_send_header() errors in the perl module, though this doesn't seem to be easy enough.