sip: use Language::Python.

Library/Formula/sip.rb

@@ -14,16 +14,6 @@ class Sip < Formula
     odie "sip: --with-python3 must be specified when using --without-python"
   end
 
-  def pythons
-    pythons = []
-    ["python", "python3"].each do |python|
-      next if build.without? python
-      version = /\d\.\d/.match `#{python} --version 2>&1`
-      pythons << [python, version]
-    end
-    pythons
-  end
-
   def install
     if build.head?
       # Link the Mercurial repository into the download directory so
@@ -33,7 +23,7 @@ def install
       system "python", "build.py", "prepare"
     end
 
-    pythons.each do |python, version|
+    Language::Python.each_python(build) do |python, version|
       # Note the binary `sip` is the same for python 2.x and 3.x
       system python, "configure.py",
                      "--deployment-target=#{MacOS.version}",
@@ -43,7 +33,7 @@ def install
                      "--sipdir=#{HOMEBREW_PREFIX}/share/sip"
       system "make"
       system "make", "install"
-      system "make", "clean" if pythons.length > 1
+      system "make", "clean"
     end
   end