net: do not modify shared test variable in TestDNSReadConfig
Fixes #56542
Change-Id: I294856f8fb4d49393310ec92ab40fb7d841b6570
GitHub-Last-Rev:
a4563400af816caa6119775b7b01b51134c62149
GitHub-Pull-Request: golang/go#56545
Reviewed-on: https://go-review.googlesource.com/c/go/+/447198
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>