bpo-43952: Fix multiprocessing Listener authkey bug (GH-25845) #4

Job	Run time
i686-pc-windows-msvc/msvc (Debug)	16m 21s
i686-pc-windows-msvc/msvc (Release)	20m 34s
x86_64-pc-windows-msvc/msvc (Debug)	16m 41s
x86_64-pc-windows-msvc/msvc (Release)	23m 18s
x86_64-apple-darwin/clang (Debug)	10m 32s
x86_64-apple-darwin/clang (Release)	15m 47s
aarch64-apple-darwin/clang (Debug)	8m 18s
aarch64-apple-darwin/clang (Release)	11m 58s
x86_64-unknown-linux-gnu/gcc (Debug)	1h 0m 13s
x86_64-unknown-linux-gnu/gcc (Release)	17m 32s
x86_64-unknown-linux-gnu/clang (Debug)	10m 11s
x86_64-unknown-linux-gnu/clang (Release)	13m 49s
aarch64-unknown-linux-gnu/gcc (Debug)	59m 1s
aarch64-unknown-linux-gnu/gcc (Release)	48m 20s
aarch64-unknown-linux-gnu/clang (Debug)	53m 57s
aarch64-unknown-linux-gnu/clang (Release)	30m 21s
	6h 56m 53s

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