CircleCI succeeds in pulling the docker images without this

It says "Warning!" but then says it is going to use its own credentials.
Great.  Just what I want.

.circleci/config.yml

@@ -15,72 +15,49 @@ workflows:
   ci:
     jobs:
       # Start with jobs testing various platforms.
-
+      - "debian-9":
-      - "debian-9": &DOCKERHUB_CONTEXT
-          {}
-
       - "debian-10":
-          <<: *DOCKERHUB_CONTEXT
           requires:
             - "debian-9"
 
       - "ubuntu-20-04":
-          <<: *DOCKERHUB_CONTEXT
       - "ubuntu-18-04":
-          <<: *DOCKERHUB_CONTEXT
           requires:
             - "ubuntu-20-04"
       - "ubuntu-16-04":
-          <<: *DOCKERHUB_CONTEXT
           requires:
             - "ubuntu-20-04"
 
       - "fedora-29":
-          <<: *DOCKERHUB_CONTEXT
       - "fedora-28":
-          <<: *DOCKERHUB_CONTEXT
           requires:
             - "fedora-29"
 
       - "centos-8":
-          <<: *DOCKERHUB_CONTEXT
-
       - "nixos-19-09":
-          <<: *DOCKERHUB_CONTEXT
 
       # Test against PyPy 2.7
       - "pypy27-buster":
-          <<: *DOCKERHUB_CONTEXT
 
       # Just one Python 3.6 configuration while the port is in-progress.
       - "python36":
-          <<: *DOCKERHUB_CONTEXT
 
       # Other assorted tasks and configurations
       - "lint":
-          <<: *DOCKERHUB_CONTEXT
       - "pyinstaller":
-          <<: *DOCKERHUB_CONTEXT
       - "deprecations":
-          <<: *DOCKERHUB_CONTEXT
       - "c-locale":
-          <<: *DOCKERHUB_CONTEXT
       # Any locale other than C or UTF-8.
       - "another-locale":
-          <<: *DOCKERHUB_CONTEXT
 
       - "integration":
-          <<: *DOCKERHUB_CONTEXT
           requires:
             # If the unit test suite doesn't pass, don't bother running the
             # integration tests.
             - "debian-9"
 
       - "typechecks":
-          <<: *DOCKERHUB_CONTEXT
-
       - "docs":
-          <<: *DOCKERHUB_CONTEXT
 
   images:
     # Build the Docker images used by the ci jobs.  This makes the ci jobs