The postgres module's own secrets move from /var/lib/postgres, the postgresql
package's directory, to its directory under /var/lib/mesh (mesh-catalog,
fix/1873-system-state-dirs). Genesis writes the store's superuser file at the
module's own-secret path, so the store it raises is the one the module adopts in
place: StoreSuperuserFile follows, to /var/lib/mesh/postgres/superuser.secret.
A directory genesis makes on the way is 0755, the mode of the mesh's directories,
and only the credential's own is 0700: MkdirAll at 0700 would have closed
/var/lib/mesh on a machine that had none yet.
jschoubben
de809d7e0a