making mp2 work again #1547

Job	Run time
macos-latest: clang++ Release Threads	34m 39s
macos-latest: clang++ Release OneTBB	2m 55s
macos-latest: clang++ Release PaRSEC	2m 43s
ubuntu-20.04: /usr/bin/g++-9 Release Threads	49m 25s
ubuntu-20.04: /usr/bin/g++-9 Release OneTBB	2m 23s
ubuntu-20.04: /usr/bin/g++-9 Release PaRSEC	3m 17s
macos-latest: clang++ Debug Threads	21m 16s
macos-latest: clang++ Debug OneTBB	3m 20s
macos-latest: clang++ Debug PaRSEC	4m 11s
ubuntu-20.04: /usr/bin/g++-9 Debug Threads	58m 7s
ubuntu-20.04: /usr/bin/g++-9 Debug OneTBB	2m 26s
ubuntu-20.04: /usr/bin/g++-9 Debug PaRSEC	4m 46s
	3h 9m 28s

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