Two neighbor step in char 0 #16876

Job	Run time
doctest (1.10, ubuntu-latest)	25m 24s
doctest (1.11-nightly, ubuntu-latest)	25m 37s
doctest (nightly, ubuntu-latest)	26m 51s
doctest (1.10, ubuntu-latest, depwarn=error)	27m 36s
test (1.6, short, ubuntu-latest)	57m 37s
doctest (1.10, macOS, RPTU)	12m 57s
test (1.6, long, ubuntu-latest)	49m 55s
test (1.10, short, ubuntu-latest)	1h 1m 21s
test (1.10, long, ubuntu-latest)	6m 48s
test (1.11-nightly, short, ubuntu-latest)	1h 0m 57s
test (1.11-nightly, long, ubuntu-latest)	46m 49s
test (nightly, short, ubuntu-latest)	56m 33s
test (nightly, long, ubuntu-latest)	44m 30s
test (1.10, short, ubuntu-latest, depwarn=error)	1h 3m 7s
test (1.10, long, ubuntu-latest, depwarn=error)	35m 41s
test (1.10, short, macOS, RPTU)	14m 19s
test (1.10, long, macOS, RPTU)	12m 8s
test (1.10, book, ubuntu-latest)	39m 48s
test (nightly, book, ubuntu-latest)	54m 8s
	12h 2m 6s

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