Apply tests to new HEAD format

Library/Homebrew/test/test_formula.rb

@@ -272,14 +272,14 @@ class FormulaTests < Homebrew::TestCase
     assert_equal PkgVersion.parse("1.0_1"), f.pkg_version
   end
 
-  def test_head_ignores_revisions
+  def test_head_uses_revisions
     f = formula("test", Pathname.new(__FILE__).expand_path, :head) do
       url "foo-1.0.bar"
       revision 1
       head "foo"
     end
 
-    assert_equal PkgVersion.parse("HEAD"), f.pkg_version
+    assert_equal PkgVersion.parse("HEAD_1"), f.pkg_version
   end
 
   def test_legacy_options

Library/Homebrew/test/test_pkg_version.rb

@@ -35,7 +35,8 @@ class PkgVersionTests < Homebrew::TestCase
     assert_equal "1.0_1", PkgVersion.new(Version.new("1.0"), 1).to_s
     assert_equal "1.0", PkgVersion.new(Version.new("1.0"), 0).to_s
     assert_equal "1.0", PkgVersion.new(Version.new("1.0"), 0).to_s
-    assert_equal "HEAD", PkgVersion.new(Version.new("HEAD"), 1).to_s
+    assert_equal "HEAD_1", PkgVersion.new(Version.create("HEAD"), 1).to_s
+    assert_equal "HEAD-ffffff_1", PkgVersion.new(Version.create("HEAD-ffffff"), 1).to_s
   end
 
   def test_hash