Change mspec/spec to us gitmodules

.gitmodules

@@ -1,3 +1,6 @@
 [submodule "spec/ruby_spec"]
 	path = spec/ruby_spec
 	url = https://github.com/ruby/spec
+[submodule "spec/mspec"]
+	path = spec/mspec
+	url = https://github.com/ruby/mspec

.travis.yml

@@ -19,7 +19,7 @@ matrix:
   allow_failures:
   - env: RUST_BACKTRACE=1 ENCODING=true TEST_MONKEYPATCHES=true WITH_REGRESSION=true
 before_install:
-- gem install bundler -v 1.14.5
+- gem install bundler --pre
 - curl -sSf https://static.rust-lang.org/rustup.sh | sudo sh -s -- --channel=nightly
 - bundle && bundle exec rake build_src && rake clean_src
 script: bundle exec rake test

Rakefile

@@ -69,12 +69,12 @@ Rake::TestTask.new(minitest: :build_lib) do |t|
 end
 
 task test: [:cargo, :minitest, :lint] do |_t|
-  exec 'mspec --format spec core/file/basename core/file/extname core/file/dirname library/pathname'
+  exec 'spec/mspec/bin/mspec --format spec core/file/basename core/file/extname core/file/dirname library/pathname'
 end
 
 desc "Full mspec results w/o encoding"
 task :mspec_full do
-  exec %(bash -c "TEST_MONKEYPATCHES=true WITH_REGRESSION=true mspec --format spec core/file/basename core/file/extname core/file/dirname library/pathname")
+  exec %(bash -c "TEST_MONKEYPATCHES=true WITH_REGRESSION=true spec/mspec/bin/mspec --format spec core/file/basename core/file/extname core/file/dirname library/pathname")
 end
 
 desc "Full mspec results w/ encoding"