Fixes#3837
```
$ go test google.golang.org/grpc/...
ok google.golang.org/grpc 24.275s
? google.golang.org/grpc/balancer [no test files]
? google.golang.org/grpc/balancer/base [no test files]
ok google.golang.org/grpc/balancer/grpclb 7.271s
? google.golang.org/grpc/balancer/grpclb/grpc_lb_v1 [no test files]
ok google.golang.org/grpc/balancer/roundrobin 0.427s
ok google.golang.org/grpc/benchmark 0.006s [no tests to run]
? google.golang.org/grpc/benchmark/benchmain [no test files]
? google.golang.org/grpc/benchmark/benchresult [no test files]
? google.golang.org/grpc/benchmark/client [no test files]
? google.golang.org/grpc/benchmark/grpc_testing [no test files]
ok google.golang.org/grpc/benchmark/latency 1.012s
ok google.golang.org/grpc/benchmark/primitives 0.036s [no tests to run]
? google.golang.org/grpc/benchmark/server [no test files]
? google.golang.org/grpc/benchmark/stats [no test files]
? google.golang.org/grpc/benchmark/worker [no test files]
? google.golang.org/grpc/binarylog/grpc_binarylog_v1 [no test files]
? google.golang.org/grpc/channelz/grpc_channelz_v1 [no test files]
ok google.golang.org/grpc/channelz/service 0.024s
ok google.golang.org/grpc/codes 0.006s
? google.golang.org/grpc/connectivity [no test files]
ok google.golang.org/grpc/credentials 0.014s
ok google.golang.org/grpc/credentials/alts 0.009s
? google.golang.org/grpc/credentials/alts/internal [no test files]
ok google.golang.org/grpc/credentials/alts/internal/authinfo 0.006s
ok google.golang.org/grpc/credentials/alts/internal/conn 0.133s
ok google.golang.org/grpc/credentials/alts/internal/handshaker 0.045s
ok google.golang.org/grpc/credentials/alts/internal/handshaker/service 0.013s
? google.golang.org/grpc/credentials/alts/internal/proto/grpc_gcp [no test files]
? google.golang.org/grpc/credentials/alts/internal/testutil [no test files]
? google.golang.org/grpc/credentials/google [no test files]
? google.golang.org/grpc/credentials/oauth [no test files]
? google.golang.org/grpc/encoding [no test files]
? google.golang.org/grpc/encoding/gzip [no test files]
ok google.golang.org/grpc/encoding/proto 0.075s
? google.golang.org/grpc/examples/helloworld/greeter_client [no test files]
? google.golang.org/grpc/examples/helloworld/greeter_server [no test files]
? google.golang.org/grpc/examples/helloworld/helloworld [no test files]
ok google.golang.org/grpc/examples/helloworld/mock_helloworld 0.011s
? google.golang.org/grpc/examples/oauth/client [no test files]
? google.golang.org/grpc/examples/oauth/server [no test files]
? google.golang.org/grpc/examples/route_guide/client [no test files]
ok google.golang.org/grpc/examples/route_guide/mock_routeguide 0.039s
? google.golang.org/grpc/examples/route_guide/routeguide [no test files]
? google.golang.org/grpc/examples/route_guide/server [no test files]
? google.golang.org/grpc/examples/rpc_errors/client [no test files]
? google.golang.org/grpc/examples/rpc_errors/server [no test files]
ok google.golang.org/grpc/grpclog 0.007s
? google.golang.org/grpc/grpclog/glogger [no test files]
ok google.golang.org/grpc/health 0.005s
? google.golang.org/grpc/health/grpc_health_v1 [no test files]
? google.golang.org/grpc/internal [no test files]
? google.golang.org/grpc/internal/backoff [no test files]
ok google.golang.org/grpc/internal/binarylog 0.006s
ok google.golang.org/grpc/internal/channelz 0.012s
? google.golang.org/grpc/internal/envconfig [no test files]
? google.golang.org/grpc/internal/grpcrand [no test files]
ok google.golang.org/grpc/internal/grpcsync 0.013s
ok google.golang.org/grpc/internal/leakcheck 4.052s
? google.golang.org/grpc/internal/syscall [no test files]
ok google.golang.org/grpc/internal/testutils 0.002s
ok google.golang.org/grpc/internal/transport 81.968s
? google.golang.org/grpc/interop [no test files]
? google.golang.org/grpc/interop/alts/client [no test files]
? google.golang.org/grpc/interop/alts/server [no test files]
? google.golang.org/grpc/interop/client [no test files]
? google.golang.org/grpc/interop/fake_grpclb [no test files]
? google.golang.org/grpc/interop/grpc_testing [no test files]
? google.golang.org/grpc/interop/http2 [no test files]
? google.golang.org/grpc/interop/server [no test files]
? google.golang.org/grpc/keepalive [no test files]
ok google.golang.org/grpc/metadata 0.006s
ok google.golang.org/grpc/naming 0.159s
? google.golang.org/grpc/peer [no test files]
ok google.golang.org/grpc/reflection 0.016s
? google.golang.org/grpc/reflection/grpc_reflection_v1alpha [no test files]
? google.golang.org/grpc/reflection/grpc_testing [no test files]
? google.golang.org/grpc/reflection/grpc_testingv3 [no test files]
? google.golang.org/grpc/resolver [no test files]
ok google.golang.org/grpc/resolver/dns 1.370s
? google.golang.org/grpc/resolver/manual [no test files]
? google.golang.org/grpc/resolver/passthrough [no test files]
ok google.golang.org/grpc/stats 0.104s
? google.golang.org/grpc/stats/grpc_testing [no test files]
ok google.golang.org/grpc/status 0.017s
? google.golang.org/grpc/stress/client [no test files]
? google.golang.org/grpc/stress/grpc_testing [no test files]
? google.golang.org/grpc/stress/metrics_client [no test files]
? google.golang.org/grpc/tap [no test files]
ok google.golang.org/grpc/test 33.866s
ok google.golang.org/grpc/test/bufconn 0.005s
? google.golang.org/grpc/test/codec_perf [no test files]
? google.golang.org/grpc/test/go_vet [no test files]
? google.golang.org/grpc/test/grpc_testing [no test files]
```
Jacob Hoffman-Andrews