Decouple pathname from bottles

Pathname is one of the basic building block classes in Homebrew, and as
such it is preferrable that `require`ing it does not drag in other
Homebrew code; thus avoiding circular dependency situations. Its
dependency on bottles.rb gave it an implicit dependency on formula.rb,
among other things.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/bottles.rb

@@ -56,11 +56,11 @@ def bottle_native_regex
 end
 
 def bottle_regex
-  /(\.[a-z]+\.bottle\.(\d+\.)?tar\.gz)$/
+  Pathname::BOTTLE_EXTNAME_RX
 end
 
 def old_bottle_regex
-  /((\.[a-z]+)?[\.-]bottle\.tar\.gz)$/
+  Pathname::OLD_BOTTLE_EXTNAME_RX
 end
 
 def bottle_base_url

Library/Homebrew/extend/pathname.rb

@@ -1,11 +1,13 @@
 require 'pathname'
-require 'bottles'
 require 'mach'
 
 # we enhance pathname to make our code more readable
 class Pathname
   include MachO
 
+  BOTTLE_EXTNAME_RX = /(\.[a-z]+\.bottle\.(\d+\.)?tar\.gz)$/
+  OLD_BOTTLE_EXTNAME_RX = /((\.[a-z]+)?[\.-]bottle\.tar\.gz)$/
+
   def install *sources
     results = []
     sources.each do |src|
@@ -122,8 +124,10 @@ class Pathname
   # extended to support common double extensions
   alias extname_old extname
   def extname
-    return $1 if to_s =~ bottle_regex
-    return $1 if to_s =~ old_bottle_regex
+    BOTTLE_EXTNAME_RX.match to_s
+    return $1 if $1
+    OLD_BOTTLE_EXTNAME_RX.match to_s
+    return $1 if $1
     /(\.(tar|cpio)\.(gz|bz2|xz|Z))$/.match to_s
     return $1 if $1
     return File.extname(to_s)