This updates the vendored docker/distribution to the current master
branch.
Note the following changes:
- The manifest package was split into manifest/schema1. Most references
to the manifest package in the engine needed to be updated to use
schema1 instead.
- Validation functions in api/v2 were replaced by the
distribution/reference package. The engine code has been updated to
use the reference package for validation where necessary. A future PR
will change the engine to use the types defined in
distribution/reference more comprehensively.
- The reference package explicitly allows double _ characters in
repository names. registry_test.go was updated for this.
- TestPullFailsWithAlteredManifest was corrupting the manifest JSON, now
that the schema1 package unmarshals the correct payload. The test is
being changed to modify the JSON without affecting its length, which
allows the pull to succeed to the point where digest validation
happens.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>