4bb475cd3c
Several improvements to error handling: - Introduce ImageConfigPullError type, wrapping errors related to downloading the image configuration blob in schema2. This allows for a more descriptive error message to be seen by the end user. - Change some logrus.Debugf calls that display errors to logrus.Errorf. Add log lines in the push/pull fallback cases to make sure the errors leading to the fallback are shown. - Move error-related types and functions which are only used by the distribution package out of the registry package. Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>