OpenBSD maintained several local patches to nginx, such as chroot [0] by default and reallocarray fixes, but it was rejected by the upstream and too big to maintain locally.

OpenBSD httpd would probably have never existed if nginx upstream reacted differently.

https://www.openbsd.org/papers/httpd-slides-asiabsdcon2015.p...

[0] The OpenBSD nginx port still includes the default chroot patch, ~8 years later, see https://raw.githubusercontent.com/sthen/nginx_chroot_patch/a... and https://github.com/openbsd/ports/blob/master/www/nginx/Makef...