backend: Fix race condition in gRPC logging
backend: Fix race condition in gRPC logging

only occurs on OSX when -test.count=>1

SchumacherFM/caddyesi,corestoreio/caddy-esi,SchumacherFM/caddyesi,corestoreio/caddy-esi,SchumacherFM/caddyesi,corestoreio/caddy-esi