ruby.git/libexec, branch ruby_2_6

Downgrade Bundler 1.17.x from 2.0.0.

2018-12-11T03:07:37+00:00

  We have the platform issue on heroku:
    * https://gist.github.com/schneems/26452540f6e2bbbcf2ea144f45f6b305
    * https://github.com/heroku/heroku-buildpack-ruby/issues/833

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66323 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Revert "Remove `libexec/bundle_ruby`"

2018-12-05T11:29:56+00:00

This reverts commit 3f708604920f2fd7a105d5f092240737add15ef1.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66220 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Remove `libexec/bundle_ruby`

2018-12-05T11:20:29+00:00

see r65979
[Bug #15291][ruby-dev:50663]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66219 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

Use stub executables generated by RubyGems istead of original executables.

2018-11-25T01:20:00+00:00

It resolved the conflict issues when invoking `gem i rdoc` and the binstub
issues with Bundler and Rails.

  [Bug #5060][ruby-core:38257][Fix GH-2023]

  * https://github.com/rubygems/rubygems/pull/2338
  * https://github.com/heroku/heroku-buildpack-ruby/issues/829

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65963 b2dd03c8-39d4-4d8f-98ff-823fe69b080e