I'm currently running PHP 5.6.6 installed on Ubuntu using the PPA provided by Ondřej Surý https://launchpad.net/~ondrej/+archive/ubuntu/php5-5.6 This is managed using Chef which isn't really relevant here.
In our builds we define exact version numbers to be installed (currently set to 5.6.6+dfsg-1+deb.sury.org~trusty+1). This has been working fine in our daily builds for the last few weeks. But this build has just failed as 5.6.7+dfsg-1+deb.sury.org~trusty+1 has just been released in the last hour and now version 5.6.6+dfsg-1+deb.sury.org~trusty+1 seems to have vanished from existence.
I have no problem running builds against new versions to make sure everything works, but this needs to be scheduled into our release strategy. How can I retain access to the previous versions on a PPA?