[rubygems/rubygems] Fixed rubocop issue: Layout/SpaceInsideBlockBraces

ruby/rubygems@77a52b011a

Author: hsbt

test/rubygems/test_gem_installer.rb

@@ -1247,7 +1247,7 @@ def test_install_does_not_leave_lockfile_for_binstub
     end
 
     assert_raise(Gem::Ext::BuildError) do
-      build_rake_in {installer.install}
+      build_rake_in { installer.install }
     end
 
     assert_path_not_exist(File.join(installer.bin_dir, "executable.lock"))