[bundler/bundler] Drop rubygems 2.5.0 and 2.5.1 support

https://github.com/bundler/bundler/commit/8ecd722b9f

lib/bundler/bundler.gemspec

@@ -32,7 +32,7 @@ Gem::Specification.new do |s|
   end
 
   s.required_ruby_version     = ">= 2.3.0"
-  s.required_rubygems_version = ">= 2.5.0"
+  s.required_rubygems_version = ">= 2.5.2"
 
   s.add_development_dependency "automatiek", "~> 0.1.0"
   s.add_development_dependency "rake",       "~> 12.0"

lib/bundler/rubygems_integration.rb

@@ -314,19 +314,6 @@ module Bundler
       end
     end
 
-    # RubyGems-generated binstubs call Kernel#gem
-    def binstubs_call_gem?
-      !provides?(">= 2.5.2")
-    end
-
-    # only 2.5.2+ has all of the stub methods we want to use, and since this
-    # is a performance optimization _only_,
-    # we'll restrict ourselves to the most
-    # recent RG versions instead of all versions that have stubs
-    def stubs_provide_full_functionality?
-      provides?(">= 2.5.2")
-    end
-
     def replace_gem(specs, specs_by_name)
       reverse_rubygems_kernel_mixin
 
@@ -335,7 +322,6 @@ module Bundler
       kernel = (class << ::Kernel; self; end)
       [kernel, ::Kernel].each do |kernel_class|
         redefine_method(kernel_class, :gem) do |dep, *reqs|
-          executables ||= specs.map(&:executables).flatten if ::Bundler.rubygems.binstubs_call_gem?
           if executables && executables.include?(File.basename(caller.first.split(":").first))
             break
           end

lib/bundler/source/git.rb

@@ -314,12 +314,10 @@ module Bundler
       # no-op, since we validate when re-serializing the gemspec
       def validate_spec(_spec); end
 
-      if Bundler.rubygems.stubs_provide_full_functionality?
-        def load_gemspec(file)
-          stub = Gem::StubSpecification.gemspec_stub(file, install_path.parent, install_path.parent)
-          stub.full_gem_path = Pathname.new(file).dirname.expand_path(root).to_s.untaint
-          StubSpecification.from_stub(stub)
-        end
+      def load_gemspec(file)
+        stub = Gem::StubSpecification.gemspec_stub(file, install_path.parent, install_path.parent)
+        stub.full_gem_path = Pathname.new(file).dirname.expand_path(root).to_s.untaint
+        StubSpecification.from_stub(stub)
       end
 
       def git_scope

lib/bundler/stub_specification.rb

@@ -63,10 +63,8 @@ module Bundler
       stub.loaded_from
     end
 
-    if Bundler.rubygems.stubs_provide_full_functionality?
-      def matches_for_glob(glob)
-        stub.matches_for_glob(glob)
-      end
+    def matches_for_glob(glob)
+      stub.matches_for_glob(glob)
     end
 
     def raw_require_paths

spec/bundler/commands/exec_spec.rb

@@ -851,7 +851,7 @@ __FILE__: #{path.to_s.inspect}
         bundle :install, :system_bundler => true, :path => "vendor/bundler"
       end
 
-      it "overrides disable_shared_gems so bundler can be found", :ruby_repo, :rubygems => ">= 2.5.2" do
+      it "overrides disable_shared_gems so bundler can be found", :ruby_repo do
         system_gems :bundler
         file = bundled_app("file_that_bundle_execs.rb")
         create_file(file, <<-RB)