errors: optimize errors.Join for single unwrappable errors
Change-Id: I10bbb782ca7234cda8c82353f2255eec5be588c9
GitHub-Last-Rev:
e5ad8fdb802e56bb36c41b4982ed27c1e0809af8
GitHub-Pull-Request: golang/go#70770
Reviewed-on: https://go-review.googlesource.com/c/go/+/635115
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>