test/rubygems: clear hooks

* test/rubygems/test_gem_commands_pristine_command.rb (setup):
  clear post_install hook to fix failures when running parallel to
  test_gem_commands_install_command.rb with -j option.

* test/rubygems/test_gem_commands_uninstall_command.rb (setup):
  ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51567 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rubygems/test_gem_commands_pristine_command.rb

@@ -5,6 +5,8 @@ class TestGemCommandsPristineCommand < Gem::TestCase
 
   def setup
     super
+    common_installer_setup
+
     @cmd = Gem::Commands::PristineCommand.new
   end
 

test/rubygems/test_gem_commands_uninstall_command.rb

@@ -5,6 +5,7 @@ class TestGemCommandsUninstallCommand < Gem::InstallerTestCase
 
   def setup
     super
+    common_installer_setup
 
     build_rake_in do
       use_ui @ui do