Guard against mismatched `--requirements-pex`. (#2392) #2568

Job	Run time
Check GitHub Organization	1s
tox -e py312-pip24_0	18m 55s
tox -e format-check,lint-check,typecheck,vendor-check,package,docs	6m 26s
tox -e py312-pip24_0-integration	41m 22s
./dtox.sh -e py27-pip20	13m 2s
./dtox.sh -e py37-pip20	16m 18s
./dtox.sh -e py311-pip20	16m 14s
./dtox.sh -e py311-pip22_3_1	15m 56s
./dtox.sh -e py311-pip23_1_2	17m 11s
./dtox.sh -e py312-pip24_0	16m 43s
./dtox.sh -e py313-pip24_0_patched	16m 13s
./dtox.sh -e pypy310-pip20	26m 19s
./dtox.sh -e pypy310-pip22_3_1	27m 5s
./dtox.sh -e pypy310-pip23_1_2	26m 35s
./dtox.sh -e py27-pip20-integration	21m 11s
./dtox.sh -e py37-pip22_3_1-integration	41m 10s
./dtox.sh -e py37-pip23_1_2-integration	41m 31s
./dtox.sh -e py311-pip20-integration	24m 40s
./dtox.sh -e py311-pip22_3_1-integration	29m 30s
./dtox.sh -e py311-pip23_1_2-integration	28m 29s
./dtox.sh -e py312-pip24_0-integration	35m 26s
./dtox.sh -e py313-pip24_0_patched-integration	42m 16s
./dtox.sh -e pypy310-pip20-integration	45m 15s
./dtox.sh -e pypy310-pip22_3_1-integration	54m 56s
./dtox.sh -e pypy310-pip23_1_2-integration	53m 33s
Gather Final Status	1s
	11h 16m 18s

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