## Assembling a new deployment directory

Given a commit to deploy, OSTree first allocates a directory for it. This is of the form `/boot/loader/entries/ostree-`osname`-`checksum`.`serial`.conf`. The `serial` is normally 0, but if a given commit is deployed more than once, it will be incremented. This is supported because the previous deployment may have configuration in `/etc` that we do not want to use or overwrite.

Now that we have a deployment directory, a 3-way merge is performed between the (by default) currently booted deployment's `/etc`, its default configuration, and the new deployment (based on its `/usr/etc`).