~/go-review/src/cmd$ go version
go version devel +320cc79002 Tue Oct 27 12:36:54 2020 +0000 linux/amd64
~/go-review/src/cmd$ go vet cmd
vendor/github.com/google/pprof/driver/driver.go:24:2: use of internal package github.com/google/pprof/internal/driver not allowed
vendor/github.com/google/pprof/driver/driver.go:25:2: use of internal package github.com/google/pprof/internal/plugin not allowed
~/go-review/src/cmd$ cd ..
~/go-review/src$ go vet cmd
I'm not actually sure whether this bug is in cmd/go or in cmd/vet.
There was a similar issue (#41358) in cmd/api which we resolved by omitting the vendored packages. However, in this case I think we really should be running vet on these packages — we just need to get go vet to interpret the imports from within those packages correctly.