Fix applied to ruby-net-ldap (#608).

git-svn-id: http://redmine.rubyforge.org/svn/trunk@1148 e93f8b46-1217-0410-a6f0-8f06a7374b81

vendor/plugins/ruby-net-ldap-0.0.4/lib/net/ber.rb

@@ -68,7 +68,7 @@ module Net
     # this can throw TypeErrors and other nasties.
     #
     def read_ber syntax=nil
-      return nil if eof?
+      return nil if (StringIO == self.class) and  eof?
 
       id = getc  # don't trash this value, we'll use it later
       tag = id & 31