Improve docker backend detection under linux during testing (#4378)

tests/integration/test_command.py

@@ -87,8 +87,8 @@ def has_pure_docker() -> bool:
                     failure = "Docker is using podman's backend, run `sudo podman-mac-helper uninstall` to disable it."
                 else:
                     failure = "Docker is using podman's backend, so we will skip running docker tests as they are high likely to fail. See https://github.com/ansible-collections/community.docker/issues/660 https://github.com/containers/podman/issues/16548"
-            elif result.stdout != "Not Found":
-                failure = "Unexpected response from Docker's default socket."
+            elif result.stdout.rstrip() not in ("Not Found", '{"message":"page not found"}'):
+                failure = f"Unexpected response from Docker's default socket {result.stdout}."
     else:
         result = run(["docker", "context", "inspect", "--format", "{{.Endpoints.docker.Host}}"])
         if result.returncode != 0: