It's currently impossible to wait until all SQLite write finish to disk.
This is not guaranteed when closing the ent DB client.
The existing code to move the cache handles the case where the
new location is on a new drive. However, due to the above issue this can
now lead to database corruption.
To avoid database corruption we now use the `os.Rename` function and
prevent moving the cache between drives until a better solution can be
implemented.
