Revert "Raise an exception when double loading a formula"

Library/Homebrew/formulary.rb

@@ -20,8 +20,6 @@ module Formulary
       raise "Formula loading disabled by HOMEBREW_DISABLE_LOAD_FORMULA!"
     end
 
-    raise "Formula #{name} has already been loaded" if const_defined?(namespace)
-
     mod = Module.new
     const_set(namespace, mod)
     begin

Library/Homebrew/test/formulary_spec.rb

@@ -27,16 +27,6 @@ describe Formulary do
   let(:bottle_dir) { Pathname.new("#{TEST_FIXTURE_DIR}/bottles") }
   let(:bottle) { bottle_dir/"testball_bottle-0.1.#{Utils::Bottles.tag}.bottle.tar.gz" }
 
-  describe "::load_formula" do
-    it "does not allow namespace repetition" do |example|
-      definition = "Foo = Class.new(Formula)"
-      namespace = "Test#{example.description.hash.abs}"
-      subject.load_formula("foo", "bar", definition, namespace)
-      expect { subject.load_formula("foo", "bar", definition, namespace) }
-        .to raise_error RuntimeError, /already.* loaded/
-    end
-  end
-
   describe "::class_s" do
     it "replaces '+' with 'x'" do
       expect(subject.class_s("foo++")).to eq("Fooxx")