Merge pull request #958 from andyleiserson/field-cleanup #212

Job	Run time
Additional Builds and Concurrency Tests	7m 14s
Basic Checks	6m 45s
miri	2m 17s
Measure coverage	17m 59s
Release builds and tests	11m 43s
sanitize (address)	4m 25s
sanitize (address, multi-threading)	6m 1s
sanitize (leak)	10m 59s
sanitize (leak, multi-threading)	3m 24s
	1h 10m 47s

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