Wrap cellar compatibility check in a method

Library/Homebrew/bottles.rb

@@ -14,7 +14,7 @@ def install_bottle? f, options={:warn=>false}
   return false unless f.pour_bottle?
   return false unless f.bottle
 
-  if f.bottle.cellar != :any && f.bottle.cellar != HOMEBREW_CELLAR.to_s
+  unless f.bottle.compatible_cellar?
     if options[:warn]
       opoo "Building source; cellar of #{f}'s bottle is #{f.bottle.cellar}"
     end

Library/Homebrew/software_spec.rb

@@ -121,6 +121,10 @@ class Bottle
     @cellar = spec.cellar
     @revision = spec.revision
   end
+
+  def compatible_cellar?
+    cellar == :any || cellar == HOMEBREW_CELLAR.to_s
+  end
 end
 
 class BottleSpecification