Version info, both which exhibit this behaviour:-
nginx version: nginx/0.8.53
TLS SNI support enabled
configure arguments: --prefix=/usr/local/etc/nginx --with-cc-opt='-I /usr/local/include' --with-ld-opt='-L /usr/local/lib' --conf-path=/usr/local/etc/nginx/nginx.conf --sbin-path=/usr/local/sbin/nginx --pid-path=/var/run/nginx.pid --error-log-path=/var/log/nginx-error.log --user=www --group=www --with-file-aio --http-client-body-temp-path=/var/tmp/nginx/client_body_temp --http-fastcgi-temp-path=/var/tmp/nginx/fastcgi_temp --http-proxy-temp-path=/var/tmp/nginx/proxy_temp --http-scgi-temp-path=/var/tmp/nginx/scgi_temp --http-uwsgi-temp-path=/var/tmp/nginx/uwsgi_temp --http-log-path=/var/log/nginx-access.log --with-http_flv_module --with-http_geoip_module --with-http_gzip_static_module --add-module=/usr/ports/www/nginx-devel/work/nginx_mod_h264_streaming-2.2.7 --with-http_realip_module --with-http_ssl_module --with-http_stub_status_module --with-pcre --add-module=/usr/ports/www/nginx-devel/work/passenger-3.0.0/ext/nginx

nginx version: nginx/0.8.49
configure arguments: --prefix=/usr/local/etc/nginx --with-cc-opt='-I /usr/local/include' --with-ld-opt='-L /usr/local/lib' --conf-path=/usr/local/etc/nginx/nginx.conf --sbin-path=/usr/local/sbin/nginx --pid-path=/var/run/nginx.pid --error-log-path=/var/log/nginx-error.log --user=www --group=www --with-file-aio --http-client-body-temp-path=/var/tmp/nginx/client_body_temp --http-proxy-temp-path=/var/tmp/nginx/proxy_temp --http-fastcgi-temp-path=/var/tmp/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/tmp/nginx/uwsgi_temp --http-log-path=/var/log/nginx-access.log --with-http_flv_module --with-http_geoip_module --with-http_gzip_static_module --add-module=/usr/ports/www/nginx-devel/work/nginx_mod_h264_streaming-2.2.7 --with-http_realip_module --with-http_stub_status_module --add-module=/usr/ports/www/nginx-devel/work/nginx_upload_module-2.0.12 --add-module=/usr/ports/www/nginx-devel/work/nginx_uploadprogress_module-0.8 --with-pcre