Lock gRPC gem to 1.8

Given 1.9 has issues we're aware of, for now we're locking to 1.8.
Closes gitlab-org/gitaly#1059 and will probably be removed if 1.10 is
tested an deemed ok.

Gemfile

@@ -427,6 +427,10 @@ end
 
 # Gitaly GRPC client
 gem 'gitaly-proto', '~> 0.87.0', require: 'gitaly'
+# Explicitly lock grpc as we know 1.9 is bad
+# 1.10 is still being tested. See gitlab-org/gitaly#1059
+gem 'grpc', '~> 1.8.3'
+
 # Locked until https://github.com/google/protobuf/issues/4210 is closed
 gem 'google-protobuf', '= 3.5.1'
 

Gemfile.lock

@@ -1108,6 +1108,7 @@ DEPENDENCIES
   grape-entity (~> 0.6.0)
   grape-route-helpers (~> 2.1.0)
   grape_logging (~> 1.7)
+  grpc (~> 1.8.3)
   gssapi
   haml_lint (~> 0.26.0)
   hamlit (~> 2.6.1)