In app_generator, fix hardcoded bundle call to derive the bundle ex…

…ecutable name from Thor::Util.ruby_command.

This ensures that eg. when `rails` is called from `ruby1.9`, `bundle1.9` is called.

railties/lib/generators/rails/app/app_generator.rb

@@ -175,7 +175,8 @@ def apply_rails_template
     end
 
     def bundle_if_dev_or_edge
-      run "bundle install" if dev_or_edge?
+      bundle_command = Thor::Util.ruby_command.sub(%r[ruby(?=[^/]*$)], 'bundle')
+      run "#{bundle_command} install" if dev_or_edge?
     end
 
     protected