cmd/go: use clean GOCACHE in TestNewReleaseRebuildsStalePackagesInGOPATH
Now that most GOROOT packages do not have install targets, their
staleness depends on whether their builds have been cached. That means
that, from a clean cache, once
TestNewReleaseRebuildsStalePackagesInGOPATH builds certain targets, they
will stay non-stale for the second run of the test, becasue the will
still be in the cache. So the first run of the test from a clean cache
will pass and the second will fail. Set GOCACHE to a temporary directory
in the test to use a clean cache and avoid this.
Change-Id: I91f954138a4723d81545134441148badbfc515f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/448018 Reviewed-by: Bryan Mills <bcmills@google.com> Reviewed-by: Than McIntosh <thanm@google.com>
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>