Revert r28200.

It caused many failures on test-all and following is SEGV.
./ruby -e 'require %!#{"foo/" * 10000}foo!'

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@28245 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 9 insertions, 33 deletions

diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index 1dee815a15..d2e0f2cb5d 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -1020,6 +1020,8 @@ end
 
 module Kernel
 
+  undef gem if respond_to? :gem # defined in gem_prelude.rb on 1.9
+
   ##
   # Use Kernel#gem to activate a specific version of +gem_name+.
   #
@@ -1096,34 +1098,13 @@ end
 
 require 'rubygems/config_file'
 
-class << Gem
-  verbose, debug = $VERBOSE, $DEBUG
-  $VERBOSE = $DEBUG = nil
-
-  ##
-  #
-  # Called from the custom_require to attempt to activate +path+
-  # Internal use only.
-
-  def try_activate(path) # :doc:
-    spec = Gem.searcher.find(path)
-    return false unless spec
-
-    Gem.activate(spec.name, "= #{spec.version}")
-    return true
-  end
-
-ensure
-  $VERBOSE, $DEBUG = verbose, debug
-end
-
 ##
 # Enables the require hook for RubyGems.
 #
 # Ruby 1.9 allows --disable-gems, so we require it when we didn't detect a Gem
 # constant at rubygems.rb load time.
 
-require 'rubygems/custom_require'
+require 'rubygems/custom_require' if gem_disabled or RUBY_VERSION < '1.9'
 
 Gem.clear_paths
 
diff --git a/lib/rubygems/custom_require.rb b/lib/rubygems/custom_require.rb
index 36e3c78911..43b3136b60 100644
--- a/lib/rubygems/custom_require.rb
+++ b/lib/rubygems/custom_require.rb
@@ -4,6 +4,8 @@
 # See LICENSE.txt for permissions.
 #++
 
+require 'rubygems'
+
 module Kernel
 
   ##
@@ -29,17 +31,10 @@ module Kernel
     gem_original_require path
   rescue LoadError => load_error
     if load_error.message.end_with?(path) and
-        begin
-          Gem.try_activate(path)
-        rescue Gem::LoadError => load_error
-          pat = "#{__FILE__}:#{__LINE__-2}:in "
-          bt = load_error.backtrace
-          num = bt.index {|e| e.start_with?(pat)} and bt.shift(num+2)
-          raise load_error
-        end
-      retry
+       spec = Gem.searcher.find(path) then
+      Gem.activate(spec.name, "= #{spec.version}")
+      gem_original_require path
     else
-      load_error.backtrace.shift(2)
       raise load_error
     end
   end
@@ -47,5 +42,5 @@ module Kernel
   private :require
   private :gem_original_require
 
-end unless Kernel.private_method_defined?(:gem_original_require)
+end