image: do actual RootFS.DiffIDs copying in Clone()
append(newRoot.DiffIDs) without element does nothing,
so it's probably not what was intended. Changed code
to perform a slice copying instead.
Fixes #38834.
Signed-off-by: Iskander Sharipov <quasilyte@gmail.com>
(cherry picked from commit 3429e9993085520ac902fef2ef6aabd57080bd36)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>