This package was only used for the deprecated "shortid" syntax. Now that
support for this syntax was removed, we can also remove this package.
This patch deprecates and removes the package, adding temporary aliases pointing
to the new location to ease migration from docker/distribution to the new
distribution/distribution/v3. We should remove those aliases in a future update.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>