Prevent future problems like we earlier with go.mod replace directives
(e.g. removing our certstore replace in 6d6cf88d82 or wireguard-go
in ea5ee6f87c, both of which were reactions to problems caused by
go.mod replace in non-root modules, often because people are using tsnet
as a library from another module)
Updates #cleanup
Change-Id: I766715cfa7ce7021460ba4933bd2fa977c3081d2
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Brad Fitzpatrick