merges r20257 from trunk into ruby_1_9_1.

fixed NoMethodError problem from NaHi [ruby-dev:37110].

git-svn-id: http://svn.ruby-lang.org/repos/ruby/branches/ruby_1_9_1@20308 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/drb/drb.rb b/lib/drb/drb.rb
index 0e6212838..13a89de07 100644
--- a/lib/drb/drb.rb
+++ b/lib/drb/drb.rb
@@ -1208,6 +1208,7 @@ module DRb
     end
 
     def alive?  # :nodoc:
+      return false unless @protocol
       @protocol.alive?
     end
   end