Fix 'I/O operation on closed file' and 'Form data has been processed already' upon redirect on multipart data #5976

Job	Run time
Generate llhttp sources	5s
Linter	1m 2s
Test (3.9, ubuntu, false)	5m 20s
Test (3.9, macos, false)	4m 29s
Test (3.9, windows, false)	7m 10s
Test (3.9, Y, ubuntu, false)	7m 13s
Test (3.10, ubuntu, false)	6m 54s
Test (3.10, macos, false)	4m 21s
Test (3.10, windows, false)	7m 13s
Test (3.10, Y, ubuntu, false)	7m 21s
Test (3.11, ubuntu, false)	5m 30s
Test (3.11, macos, false)	5m 38s
Test (3.11, windows, false)	7m 8s
Test (3.11, Y, ubuntu, false)	7m 0s
Test (3.12, ubuntu, false)	6m 15s
Test (3.12, macos, false)	4m 50s
Test (3.12, windows, false)	7m 55s
Test (3.12, Y, ubuntu, false)	6m 58s
Test (pypy-3.9, Y, ubuntu, false)	12m 43s
Test (ubuntu, 3.13, true, Y)	1m 19s
check	2s
Pre-Deploy	0s
Tarball	0s
Build wheels on ${{ matrix.os }} ${{ matrix.qemu }}	0s
Deploy	0s
	1h 56m 26s

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