Reorganize flow in pkg/docker/config
Reorganize flow in pkg/docker/config

By construction of pkg/errors.WithStack
 / pkg/errors.WithMessage / pkg/errors.Wrap*,
pkg/errors.Cause() can only return nil if the
error is nil.

Move that away from the error handling code.

Signed-off-by: Miloslav Trmač <9c008e38982a5397deb855345fb164f0558459ae@redhat.com>

containers/image,containers/image