[rubygems/rubygems] Revert "Improve default gem handling"

This reverts commit https://github.com/rubygems/rubygems/commit/091b4fcf2b99.

https://github.com/rubygems/rubygems/commit/dcade3235f

2 files changed, 6 insertions, 2 deletions

diff --git a/lib/bundler/rubygems_integration.rb b/lib/bundler/rubygems_integration.rb
index 571b303816..fdbe85b4d2 100644
--- a/lib/bundler/rubygems_integration.rb
+++ b/lib/bundler/rubygems_integration.rb
@@ -509,7 +509,7 @@ module Bundler
     end
 
     def all_specs
-      Gem::Specification.stubs.reject(&:default_gem?).map do |stub|
+      Gem::Specification.stubs.map do |stub|
         StubSpecification.from_stub(stub)
       end
     end
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
index 7e0b007006..dfcedb5b16 100644
--- a/lib/bundler/source/rubygems.rb
+++ b/lib/bundler/source/rubygems.rb
@@ -225,7 +225,11 @@ module Bundler
         cached_path = cached_path(spec)
         if cached_path.nil?
           remote_spec = remote_specs.search(spec).first
-          cached_path = fetch_gem(remote_spec)
+          if remote_spec
+            cached_path = fetch_gem(remote_spec)
+          else
+            Bundler.ui.warn "#{spec.full_name} is built in to Ruby, and can't be cached because your Gemfile doesn't have any sources that contain it."
+          end
         end
         cached_path
       end