Arcanist complained about not being able to verify the HTTPS connection.

The CA cert was integrated into the systems ca-bundle. I could successfully use "curl https://phabricator.local.domain". Only arc complained about not being able to verify.

"curl-config --ca" points to:
RHEL6: /etc/pki/tls/certs/ca-bundle.crt (updated by update-ca-trust)
Ubuntu 14.04: /etc/ssl/certs/ca-certificates.crt (updated by update-ca-certificates)

Seems the PHP curl >= 5.3.7 has the curl.cainfo ption which is empty by default can't be used as default value.

I propose to set the default path to the systems ca bundle file.