Fix race condition with request handlers on shutdown #2986

Job	Run time
Linter	1m 10s
Generate llhttp sources	6s
Test (3.8, ubuntu, false)	5m 9s
Test (3.8, windows, false)	5m 17s
Test (3.8, Y, ubuntu, false)	4m 26s
Test (3.9, ubuntu, false)	6m 8s
Test (3.9, macos, false)	5m 40s
Test (3.9, windows, false)	5m 14s
Test (3.9, Y, ubuntu, false)	4m 44s
Test (3.10, ubuntu, false)	5m 37s
Test (3.10, macos, false)	5m 50s
Test (3.10, windows, false)	6m 1s
Test (3.10, Y, ubuntu, false)	5m 53s
Test (3.11, ubuntu, false)	4m 36s
Test (3.11, macos, false)	8m 48s
Test (3.11, windows, false)	6m 25s
Test (3.11, Y, ubuntu, false)	4m 43s
Test (3.12, ubuntu, false)	4m 48s
Test (3.12, macos, false)	6m 32s
Test (3.12, windows, false)	6m 16s
Test (3.12, Y, ubuntu, false)	4m 58s
Test (pypy-3.9, Y, ubuntu, false)	10m 19s
Test (ubuntu, 3.13, true, Y)	46s
check	2s
Pre-Deploy	0s
Build wheels on ${{ matrix.os }} ${{ matrix.qemu }}	0s
Tarball	0s
Deploy	0s
	1h 59m 28s

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