Track the locale in Sentry so we know which ones are failing

lib/gitlab/sentry.rb

@@ -7,6 +7,8 @@ module Gitlab
     def self.context(current_user = nil)
       return unless self.enabled?
+      Raven.tags_context(locale: I18n.locale)
+
       if current_user
         Raven.user_context(
           id: current_user.id,

spec/lib/gitlab/sentry_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Sentry do
+  describe '.context' do
+    it 'adds the locale to the tags' do
+      expect(described_class).to receive(:enabled?).and_return(true)
+
+      described_class.context(nil)
+
+      expect(Raven.tags_context[:locale]).to eq(I18n.locale.to_s)
+    end
+  end
+end