Issue #17278: Fix a crash in heapq.heappush() and heapq.heappop() when the list is being resized concurrently.
Fix Issue #12921: BaseHTTPServer's send_error should send the correct error
response message when  send_error includes a message in addition to error
status. Patch contributed by Karl.
Reverting the changeset 5126e62c60af made for Issue #12921