HZ: avoid convergence if bisected #18

Job	Run time
test (1.6, x64, ubuntu-latest)	2m 15s
test (1.6, x64, windows-latest)	9m 45s
test (1.6, x64, macOS-latest)	3m 4s
test (1.6, x86, ubuntu-latest)	2m 41s
test (1.6, x86, windows-latest)	10m 57s
test (1, x64, ubuntu-latest)	1m 29s
test (1, x64, windows-latest)	2m 6s
test (1, x64, macOS-latest)	2m 34s
test (1, x86, ubuntu-latest)	1m 48s
test (1, x86, windows-latest)	3m 4s
test (nightly, x64, ubuntu-latest)	3m 0s
test (nightly, x64, windows-latest)	4m 32s
test (nightly, x64, macOS-latest)	3m 50s
test (nightly, x86, ubuntu-latest)	4m 35s
test (nightly, x86, windows-latest)	5m 37s
	1h 1m 17s

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