Users upgrading to PHP 8.1 might start observing failures with `arc`.
Commit @ychen's suggestions as a patch in tree that can be applied since
arcanist is no longer accepting patches.
Also, remove the suggestion to apply an external patch updating CA
certs. It seems that this was fixed in upstream arcanist before they
stopped accepting patches. Compare
e3659d43d8
vs
13d3a3c3b1
Link: https://secure.phabricator.com/book/phabcontrib/article/contributing_code/
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D129232
Nick Desaulniers