Previously, it was comparing against the driver name passed in by the
caller. This could lead to subtle issues when using plugins, like
"plugin" vs. "plugin:latest".
Also, remove "conflict:" prefix to improve the error message.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Upstream-commit: 53d447c5d5c85d5595d5170411189c88a135a789
Component: engine