[yyuu]

Summary

• Drain request bodies before Basic, Digest, and Digest-sess authentication can issue a challenge.
• Add regression tests that verify the body is read before authentication.

Context

WEBrick can return an authentication challenge while a streamed upload is still unread. The connection may close before the client finishes sending the body, causing intermittent resets in multipart and IO-body POST tests.

Testing

• Ruby 2.7 local: 3 regression tests / 6 assertions passed; Basic multipart and Digest IO POST: 2 tests / 3 assertions passed.
• GitHub Actions run #41788803911: attempts 1 and 3 passed all 12 matrix jobs. Attempt 2 was canceled after the Ruby 2.7 job stopped reporting progress; the authentication tests and new regression tests passed before the stall.

[yyuu]

Test only fixes. Should be safe enough to just move on... 🤞