Merge pull request #188 from cybozu-go/5607-verify-2 #878

Job	Run time
build (3Mi, incr-backup)	31m 42s
build (3Mi, change-to-standalone)	23m 19s
build (3Mi, full-backup)	28m 17s
build (3Mi, change-to-primary)	30m 29s
build (3Mi, change-to-secondary)	27m 10s
build (3Mi, backup-failure)	30m 17s
build (200Gi, various-transfer-part-size)	20m 56s
build (3Mi, !//)	37m 11s
build (10Mi, various-transfer-part-size)	23m 7s
	4h 12m 28s

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