This is causing failures on TryBots and BuildBots:
--- FAIL: TestGcSys (0.06s)
    gc_test.go:27: expected "OK\n", but got "using too much memory: 39882752 bytes\n"
FAIL

Updates #27156

Change-Id: I418bbec89002574cd583c97422e433f042c07492
Reviewed-on: https://go-review.googlesource.com/130875
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>