LUCI doesn't check the source out into a GOPATH-style layout like
trybots do. Fix the tests that relied on that.
Change-Id: I6ebaf1dce5cf831c63743f64acee332dacb7f102
Reviewed-on: https://go-review.googlesource.com/c/exp/+/506297
Run-TryBot: Heschi Kreinick <heschi@google.com>
Auto-Submit: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>