Move some exceptions

Library/Homebrew/exceptions.rb

@@ -1,9 +1,30 @@
+class UsageError <RuntimeError; end
+class FormulaUnspecifiedError <UsageError; end
+class KegUnspecifiedError <UsageError; end
 
-class NotAKegError < RuntimeError
+class MultipleVersionsInstalledError <RuntimeError
+  attr :name
+
+  def initialize name
+    @name = name
+    super "#{name} has multiple installed versions"
+  end
+end
+
+class NotAKegError < RuntimeError; end
+
+class NoSuchKegError <RuntimeError
+  attr :name
+
+  def initialize name
+    @name = name
+    super "No such keg: #{HOMEBREW_CELLAR}/#{name}"
+  end
 end
 
 class FormulaUnavailableError < RuntimeError
   attr :name
+
   def initialize name
     @name = name
     super "No available formula for #{name}"
@@ -13,6 +34,7 @@ end
 module Homebrew
   class InstallationError < RuntimeError
     attr :formula
+
     def initialize formula
       @formula = formula
     end

Library/Homebrew/extend/ARGV.rb

@@ -1,25 +1,3 @@
-class UsageError <RuntimeError; end
-class FormulaUnspecifiedError <UsageError; end
-class KegUnspecifiedError <UsageError; end
-
-class MultipleVersionsInstalledError <RuntimeError
-  attr :name
-
-  def initialize name
-    @name = name
-    super "#{name} has multiple installed versions"
-  end
-end
-
-class NoSuchKegError <RuntimeError
-  attr :name
-
-  def initialize name
-    @name = name
-    super "No such keg: #{HOMEBREW_CELLAR}/#{name}"
-  end
-end
-
 module HomebrewArgvExtension
   def named
     @named ||= reject{|arg| arg[0..0] == '-'}