This commit brings a more pedantic change in the following ambiguous case:
cat Dockerfile | docker build -f otherDockerfile -
The legacy builder does not error out and prefers the Dockerfile from stdin
while the buildkit-based one errors out.
Note that this is only in the case where stdin is a Dockerfile (not an archive)
Signed-off-by: Tibor Vass <tibor@docker.com>
82f0e1e5d8