Don't wait forever for subprocess #164

Job	Run time
Valgrind	2m 7s
Valgrind	2m 9s
Check for documentation errors	48s
Check for documentation errors	41s
Clippy nightly (optional)	32s
Clippy nightly (optional)	31s
Format	14s
Format	12s
Build+test (stable, ubuntu-latest)	1m 43s
Build+test (stable, ubuntu-latest)	2m 5s
Build+test (beta, ubuntu-latest)	1m 55s
Build+test (beta, ubuntu-latest)	1m 39s
Clang Tidy	7s
Clang Tidy	7s
Miri	1m 16s
Miri	1m 31s
Build+test (nightly, ubuntu-latest)	1m 41s
Build+test (nightly, ubuntu-latest)	1m 41s
Packaging	2m 57s
Packaging	2m 29s
Clippy	32s
Clippy	41s
	27m 38s

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