cmd/go: avoid when go.env contain GOTOOLCHAIN=local test fail
The test fail when $GOROOT/go.env contain GOTOOLCHAIN=local
because GOTOOLCHAIN=local is assumed to be a non-default value.
This CL fixed the test failure
by using go.env from the test as $GOROOT/go.env throughout the test.
Test have also been added to ensure that
when $GOROOT/go.env contain GOTOOLCHAIN=local,
GOTOOLCHAIN=local is not taken as a non-default value.
Fixes #67793
Change-Id: Ibc5057d38d36c6c55726a039de1e7c37d6935b52
GitHub-Last-Rev:
12b62464e671021320c54e251dfb1ebcb5925096
GitHub-Pull-Request: golang/go#67807
Reviewed-on: https://go-review.googlesource.com/c/go/+/590196
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>