pdns: head fixes

Closes Homebrew/homebrew#33601.

Formula/pdns.rb

@@ -1,10 +1,18 @@
-require 'formula'
+require "formula"
 
 class Pdns < Formula
-  homepage 'http://www.powerdns.com'
-  head 'https://github.com/powerdns/pdns.git'
-  url 'http://downloads.powerdns.com/releases/pdns-3.4.0.tar.bz2'
-  sha1 'b1c5bf10e03c04f707b752b5159db06179c172d9'
+  homepage "http://www.powerdns.com"
+  url "http://downloads.powerdns.com/releases/pdns-3.4.0.tar.bz2"
+  sha1 "b1c5bf10e03c04f707b752b5159db06179c172d9"
+
+  head do
+    url "https://github.com/powerdns/pdns.git"
+
+    depends_on "automake" => :build
+    depends_on "autoconf" => :build
+    depends_on "libtool"  => :build
+    depends_on "ragel"
+  end
 
   bottle do
     sha1 "be0e2cae3ab4502568b050cd1c7cadcb8a7205d9" => :yosemite
@@ -12,19 +20,21 @@ class Pdns < Formula
     sha1 "ff04dae2726cfe50b2535a96c88aa325d04d7aa1" => :mountain_lion
   end
 
-  option 'pgsql', 'Enable the PostgreSQL backend'
+  option "pgsql", "Enable the PostgreSQL backend"
 
-  depends_on 'pkg-config' => :build
-  depends_on 'boost'
-  depends_on 'lua'
-  depends_on 'sqlite'
-  depends_on :postgresql if build.include? 'pgsql'
+  depends_on "pkg-config" => :build
+  depends_on "boost"
+  depends_on "lua"
+  depends_on "sqlite"
+  depends_on :postgresql if build.include? "pgsql"
 
   def install
     args = ["--prefix=#{prefix}",
             "--with-lua",
-            "--with-sqlite3",
-            "--with-sqlite=#{Formula["sqlite"].opt_prefix}"]
+            "--with-sqlite3"]
+
+    # Specifying the sqlite prefix is no longer recognised in the HEAD.
+    args << "--with-sqlite=#{Formula["sqlite"].opt_prefix}" if build.stable?
 
     # Include the PostgreSQL backend if requested
     if build.include? "pgsql"
@@ -39,7 +49,6 @@ class Pdns < Formula
 
     # Compilation fails at polarssl if we skip straight to make install
     system "make"
-    system "make install"
-
+    system "make", "install"
   end
 end