Please be prepared to switch from “root” to “config” as the name of the config object in your config override files. This change was prompted by RFC-62 and implemented in DM-3630, which I just merged to master. Once you start using the latest version of pex_config you should make this change.
For now we do support backwards compatibility: if you have old files that use “root” then you can load them, but you will get a warning message printed to stderr. At some point we are likely to remove this backwards compatibility.
The main code change is in pex_config, but I also updated the config files in many packages.