First building blocks for Sharding API: ShardIndex and TransportIdent… #3738

Job	Run time
Basic Checks	6m 32s
Additional Builds and Concurrency Tests	6m 43s
Release builds and tests	5m 12s
sanitize (address)	4m 15s
sanitize (address, multi-threading)	6m 0s
sanitize (leak)	5m 6s
Measure coverage	9m 8s
miri	3m 56s
sanitize (leak, multi-threading)	3m 25s
	50m 17s

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