With the 1.7 release, we introduced a change to how we store registry
credentials, but the build API endpoint did not expect a change in the format
of that file. This patch fixes this problem so that you can again pull private
images during `docker build`.
Docker-DCO-1.1-Signed-off-by: Josh Hawn <josh.hawn@docker.com> (github: jlhawn)
Upstream-commit: 02c7bbefb8841e5e86a4b9d467defa668e3ea613
Component: engine