Merge rubygems master.

This is RC version of Rubygems 2.7.0.
  688fb7e83c

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60133 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rubygems/test_kernel.rb

@@ -90,4 +90,34 @@ class TestKernel < Gem::TestCase
     assert gem('a', '= 1'), "Should load"
     refute $:.any? { |p| %r{a-1/bin} =~ p }
   end
+
+  def test_gem_bundler
+    quick_gem 'bundler', '1'
+    quick_gem 'bundler', '2.a'
+
+    assert gem('bundler')
+    assert $:.any? { |p| %r{bundler-1/lib} =~ p }
+  end
+
+  def test_gem_bundler_missing_bundler_version
+    Gem::BundlerVersionFinder.stub(:bundler_version_with_reason, ["55", "reason"]) do
+      quick_gem 'bundler', '1'
+      quick_gem 'bundler', '2.a'
+
+      e = assert_raises Gem::MissingSpecVersionError do
+        gem('bundler')
+      end
+      assert_match "Could not find 'bundler' (55) required by reason.", e.message
+    end
+  end
+
+  def test_gem_bundler_inferred_bundler_version
+    Gem::BundlerVersionFinder.stub(:bundler_version_with_reason, ["1", "reason"]) do
+      quick_gem 'bundler', '1'
+      quick_gem 'bundler', '2.a'
+
+      assert gem('bundler', '>= 0.a')
+      assert $:.any? { |p| %r{bundler-1/lib} =~ p }
+    end
+  end
 end