Error calling BaseHTTPRequestHandler.end_headers()

Bug report

Bug description:

If a call is made to BaseHTTPRequestHandler.end_headers() but no headers or response have been queued, an exception is raised exposing implementation details.

    class request_handler(BaseHTTPRequestHandler):
        def do_GET(self):
            self.end_headers()

Actual result

AttributeError("'request_handler' object has no attribute '_headers_buffer'")

Expected result:

pass

flush_headers has a guard to check if the buffer has been allocated which is missing from end_headers

if hasattr(self, '_headers_buffer'):

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-131718

首先定位 CPython 的 BaseHTTPRequestHandler.end_headers() 并将其处理方式与 flush_headers() 进行比较，尤其要检查报告中描述的 _headers_buffer 保护。完成的标准是：在没有排队的标头或 response 的情况下调用 end_headers()，能够完成且不会暴露 AttributeError；开始前请检查关联的 PR gh-131718。