Occasionally I see:
--- FAIL: TestAllocations-15 (0.00 seconds)
        all_test.go:1575: 6 mallocs after 100 iterations
Tested:
$ go test -cpu=1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 reflect

R=golang-dev, dsymonds, r
CC=golang-dev
https://golang.org/cl/6354063