cmd/go/internal/vcs: don’t new errors ahead of time in gitRemoteRepo
Also make 'cmd' a const for it is in fact immutable.
Change-Id: I3373daa1775e863a378355a355325a7fbdf90485
GitHub-Last-Rev:
f6698174f53988274c75af83acb267741676b712
GitHub-Pull-Request: golang/go#63155
Reviewed-on: https://go-review.googlesource.com/c/go/+/530395
Auto-Submit: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>