Unset BUNDLE_GEMFILE when installing Gitaly

lib/tasks/gitlab/gitaly.rake

@@ -21,7 +21,7 @@ namespace :gitlab do
         create_gitaly_configuration
         # In CI we run scripts/gitaly-test-build instead of this command
         unless ENV['CI'].present?
-          Bundler.with_original_env { run_command!(%w[/usr/bin/env -u RUBYOPT] + [command]) }
+          Bundler.with_original_env { run_command!(%w[/usr/bin/env -u RUBYOPT -u BUNDLE_GEMFILE] + [command]) }
         end
       end
     end

spec/tasks/gitlab/gitaly_rake_spec.rb

@@ -41,7 +41,7 @@ describe 'gitlab:gitaly namespace rake task' do
     end
 
     describe 'gmake/make' do
-      let(:command_preamble) { %w[/usr/bin/env -u RUBYOPT] }
+      let(:command_preamble) { %w[/usr/bin/env -u RUBYOPT -u BUNDLE_GEMFILE] }
 
       before(:all) do
         @old_env_ci = ENV.delete('CI')