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

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@20257 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Nov 19 01:10:52 2008  Masatoshi SEKI  <m_seki@mva.biglobe.ne.jp>
+
+	* lib/drb/drb.rb (DRbConn::alive?): fixed NoMethodError problem
+	  from NaHi [ruby-dev:37110].
+
 Wed Nov 19 01:05:26 2008  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* cont.c (cont_mark, cont_capture, cont_restore_1): speed up

lib/drb/drb.rb

@@ -1208,6 +1208,7 @@ module DRb
     end
 
     def alive?  # :nodoc:
+      return false unless @protocol
       @protocol.alive?
     end
   end