#! /bin/sh /usr/share/dpatch/dpatch-run
## 03_disable_update_system.dpatch by James Healy <jimmy@deefa.com>
##
## All lines beginning with `## DP:' are a description of the patch.
## DP: Disable gem update --system functionality, as it can break things. Users should use apt instead

@DPATCH@
--- a/lib/rubygems/commands/update_command.rb
+++ b/lib/rubygems/commands/update_command.rb
@@ -48,18 +48,22 @@ class Gem::Commands::UpdateCommand < Gem
     hig = {}
 
     if options[:system] then
-      say "Updating RubyGems"
+      if ENV.include?('REALLY_GEM_UPDATE_SYSTEM')
+        say "Updating RubyGems"
 
-      unless options[:args].empty? then
-        raise "No gem names are allowed with the --system option"
-      end
+        unless options[:args].empty? then
+          raise "No gem names are allowed with the --system option"
+        end
 
-      rubygems_update = Gem::Specification.new
-      rubygems_update.name = 'rubygems-update'
-      rubygems_update.version = Gem::Version.new Gem::VERSION
-      hig['rubygems-update'] = rubygems_update
+        rubygems_update = Gem::Specification.new
+        rubygems_update.name = 'rubygems-update'
+        rubygems_update.version = Gem::Version.new Gem::VERSION
+        hig['rubygems-update'] = rubygems_update
 
-      options[:user_install] = false
+        options[:user_install] = false
+      else
+        fail "gem update --system is disabled on Debian, because it will overwrite the content of the rubygems Debian package, and might break your Debian system in subtle ways. The Debian-supported way to update rubygems is through apt-get, using Debian official repositories.\nIf you really know what you are doing, you can still update rubygems by setting the REALLY_GEM_UPDATE_SYSTEM environment variable, but please remember that this is completely unsupported by Debian."
+      end
     else
       say "Updating installed gems"