Building with vendored modules

I’m trying to update the FreeBSD port to 1.12.1, and I’m running into this problem:

    CC= GOOS= GOARCH= go generate -mod=vendor -tags 'pam sqlite sqlite_unlock_notify' 
go: inconsistent vendoring in /var/ports/work/usr/home/vagrant/gitea/work/gitea-1.12.1:
	src.techknowlogick.com/xgo@v0.0.0-20200602060627-a09175ea9056: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt

run 'go mod vendor' to sync, or use -mod=mod or -mod=readonly to ignore the vendor directory

I’m pulling the release archive off GitHub. Is there an additional make step that needs to be taken to use the vendored modules, or is the vendored state inconsistent in the archive?

Thanks,
Stefan

I’ve opened an issue: https://github.com/go-gitea/gitea/issues/12080