The imageRefs map was being popualted with containerID, and accessed
with an imageID which would never match.
Remove this broken code because: 1) it hasn't ever worked so isn't
necessary, and 2) because at best it would be racy
ImageDelete() should already handle preventing of removal of used
images.
Signed-off-by: Daniel Nephin <dnephin@docker.com>
Upstream-commit: 3aa4f7f0d71f04c5cc93d5e80cbdd47b0b5fdb7f
Component: engine
a0a24043be