Update pull code to consider any layer download or new tag as an update.
Update hello-world frozen image to be explicitly tagged as frozen, to not interfere with pull tests. The hello-world is used by pull tests because of its small size and there is no other official image with such a size.
fixes#11383
Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
Upstream-commit: 636037c3637eb1d09cc469cebe39ffb915bb0aa9
Component: engine
f32b25fee3