[bingdongni]

When a WebSocket server sends a response and then a normal close frame, sqlmap treats the connection as a failure and loses the response. This affects both the initial frame-count calibration and later responses with fewer frames.

Treat a normal close at a message boundary as the end of the response. Abnormal closes, truncated frames, and closure during a fragmented message still fail.

Tests:

• Python 3.12: 2,749 tests run, 15 skipped.
• PyPy 2.7 on Windows: 2,741 tests run, 34 skipped, excluding test_replication. Its six SQLite teardown errors also reproduce on unmodified master.
• Verified against a loopback WebSocket server. Also applied this change together with Preserve custom Host headers for WebSocket requests #6172 and ran their focused tests on Python 2 and 3.
• Pyflakes and git diff --check passed.