Avoid crash when passing dict to dependencies #17149

Job	Run time
Arch / PyPy	20m 51s
Arch Linux	19m 43s
Ubuntu Rolling (gcc, g++)	18m 38s
CUDA (on Arch)	7m 47s
Ubuntu Rolling (--unity=on -Ddefault_library=static, --no-unittests, gcc, g++)	13m 25s
Fedora	18m 17s
Ubuntu Rolling (-Ddefault_library=both, --no-unittests, gcc, g++)	13m 22s
Gentoo	20m 37s
Ubuntu Rolling (clang, clang++)	21m 29s
OpenSUSE	15m 32s
Ubuntu Rolling (--unity=on, --no-unittests, clang, clang++)	14m 34s
Ubuntu Bionic	14m 4s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, 0, gcc, g++)	13m 43s
Ubuntu Rolling (--cross ubuntu-armhf.json --cross linux-mingw-w64-64bit.json, --unity=on, gcc, g++)	13m 23s
	3h 45m 25s

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