Removing the ref as an argument to the Committer#parents and just using the @wiki.ref.

Updated the test to reflect the change and to test creating a wiki with a custom ref returns the correct parent for the `Committer#parents`.

lib/gollum/committer.rb

@@ -60,9 +60,9 @@ module Gollum
     # Public: The parent commits to this pending commit.
     #
     # Returns an array of Grit::Commit instances.
-    def parents(ref = @wiki.ref)
+    def parents()
       @parents ||= begin
-        arr = [@options[:parent] || @wiki.repo.commit(ref)]
+        arr = [@options[:parent] || @wiki.repo.commit(@wiki.ref)]
         arr.flatten!
         arr.compact!
         arr

test/test_committer.rb

@@ -48,7 +48,7 @@ context "Wiki" do
     end
   end
 
-  test "parents with default wiki ref" do
+  test "parents with default master ref" do
     ref = 'a8ad3c09dd842a3517085bfadd37718856dee813'
     committer = Gollum::Committer.new(@wiki)
     assert_equal ref,  committer.parents.first.sha
@@ -56,7 +56,8 @@ context "Wiki" do
 
   test "parents with custom ref" do
     ref = '60f12f4254f58801b9ee7db7bca5fa8aeefaa56b'
+    @wiki = Gollum::Wiki.new(testpath("examples/lotr.git"), :ref => ref)
     committer = Gollum::Committer.new(@wiki)
-    assert_equal ref,  committer.parents(ref).first.sha
+    assert_equal ref,  committer.parents.first.sha
   end
 end