* lib/rdoc/usage.rb: supress warning.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@9042 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rdoc/usage.rb

@@ -139,7 +139,7 @@ module RDoc
   end
 
   def RDoc.find_comment(file)
-    catch (:exit) do
+    catch(:exit) do
       # skip leading blank lines
       0 while (line = gets(file)) && (line =~ /^\s*$/)