A snapshotDir tracks its current position as part of its state, so we need
to use it via pointer rather than value so that Readdirnames can actually
update that position, or else we'll just get stuck at position zero.
In practice this wasn't hurting anything because we only call Readdir once
on our snapshots, to read the whole directory at once. Still nice to fix
to avoid a gotcha for future maintenence, though.
This is part of a general effort to move all of Terraform's non-library
package surface under internal in order to reinforce that these are for
internal use within Terraform only.
If you were previously importing packages under this prefix into an
external codebase, you could pin to an earlier release tag as an interim
solution until you've make a plan to achieve the same functionality some
other way.
Martin Atkins