The test fails now with -race, so it's disabled.
The intention is that the fix for issue 7264
will also modify this test the same way and enable it.
Reporduce with 'go test -race -issue7264 -cpu=4'.
Update #7264

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/86770043