After the addition of golang/go#35964, the import cycle error now
has the import stack attached in the message. This CL parses that
stack and attached the import cycle diagnostic to the import versus
just adding it to the first character of the .go file.
Fixesgolang/go#33085
Change-Id: I6f5f067c338879b898829951236f816aa63d9dfa
Reviewed-on: https://go-review.googlesource.com/c/tools/+/210942
Run-TryBot: Rohan Challa <rohan@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
