Flaky test: TestPromptExitCode

Description

 === FAIL: e2e/global TestPromptExitCode/plugin_upgrade (9.76s)
    cli_test.go:203: assertion failed: 
        Command:  docker plugin push registry:5000/plugin-content-trust-upgrade:next
        ExitCode: 1
        Error:    exit status 1
        Stdout:   The push refers to repository [registry:5000/plugin-content-trust-upgrade]
        7e8a4cebca1b: Preparing
        9a21d8273a47: Preparing
        65b81aa7e346: Preparing
        7e8a4cebca1b: Preparing
        9a21d8273a47: Preparing
        65b81aa7e346: Preparing
        
        Stderr:   error pushing plugin: failed to do request: Head "https://registry:5000/v2/plugin-content-trust-upgrade/blobs/sha256:9a21d8273a47451406ca7ca834220b237ea81e4ed846bf5d74d805fbaa70b9d2": http: server gave HTTP response to HTTPS client
        
        
        Failures:
        ExitCode was 1 expected 0
        Expected no error

Reproduce

https://github.com/docker/cli/actions/runs/13946393703/job/39034516260?pr=5929

Expected behavior

No response

docker version

Client:
 Version:           28.0.0-dev
 API version:       1.45 (downgraded from 1.48)
 Go version:        go1.23.7
 Git commit:        d2c85a9
 Built:             Wed Mar 19 12:22:49 2025
 OS/Arch:           linux/amd64
 Context:           default

Server: Docker Engine - Community
 Engine:
  Version:          26.1.4
  API version:      1.45 (minimum version 1.24)
  Go version:       go1.21.11
  Git commit:       de5c9cf
  Built:            Wed Jun  5 11:29:25 2024
  OS/Arch:          linux/amd64
  Experimental:     true
 containerd:
  Version:          v1.7.18
  GitCommit:        ae71819c4f5e67bb4d5ae76a6b735f29cc25774e
 runc:
  Version:          1.1.12
  GitCommit:        v1.1.12-0-g51d5e94
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

-

Additional Info

No response

Start with the e2e/global TestPromptExitCode test, especially plugin_upgrade and cli_test.go:203, then review the linked GitHub Actions job for the failure context. Reproduce the docker plugin push and investigate the HTTP-versus-HTTPS registry behavior. Done means the test reliably succeeds with exit code 0 and no error.