Accepts as valid responses to staged requests. #440

Job	Run time
B2 gcc-11	3m 2s
B2 msvc-14.2	5m 42s
CMake gcc-11 17 Debug	6m 25s
B2 clang-14	3m 15s
CMake msvc-14.2 Debug C++17	7m 30s
B2 msvc-14.3	5m 46s
CMake gcc-11 20 Release	7m 14s
CMake msvc-14.2 Release C++17	7m 40s
CMake clang-11 17 Debug	4m 20s
CMake msvc-14.3 Debug C++20	5m 38s
CMake msvc-14.3 Release C++20	5m 56s
CMake clang-11 20 Debug	4m 14s
CMake clang-13 17 Release	5m 14s
CMake clang-13 20 Release	5m 17s
CMake clang-14 17 Debug -stdlib=libc++	6m 32s
CMake clang-14 20 Release -stdlib=libc++	7m 45s
	1h 31m 30s

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