If the parser returns zero roots, don't attempt to completely remove the bundle. This may happen if, i.e., the HTTP response is 200 but has no content. An example of this may be http://go.dev/cl/535735. Change-Id: I81fc2b49c8ec813cca17fd1c807296bfb053d992 Reviewed-on: https://go-review.googlesource.com/c/crypto/+/536136 Reviewed-by: Damien Neil <dneil@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org> Auto-Submit: Roland Shoemaker <roland@golang.org>