Do not validate first_published_at against govt dates for historic or political editions

Users trying to edit previously published, historic documents are unable to do so if the `first_published_at` date was (correctly) updated in the past, since the validation prevents them from saving.  This caused a minor production incident.

This commit (along with the previous one) fixes this by ensuring the `first_published_preceeds_change_notes` validation doesn't run on historic or political editions.

Author: davidsauntson

app/models/edition.rb

@@ -451,6 +451,7 @@ def error_labels
   def first_published_preceeds_change_notes
     return if first_published_at.blank?
     return if other_editions.empty?
+    return if political? || historic?
 
     change_note_dates = other_editions.pluck(:major_change_published_at).compact.sort
 

test/unit/app/models/edition_test.rb

@@ -724,13 +724,37 @@ class EditionTest < ActiveSupport::TestCase
     assert_equal "First published date must be after the start of the current government (11/11/2009)", edition.errors.full_messages.first
   end
 
-  test "polictial editions can have their first_published_at date set before the current government " do
+  test "polictial editions can have their first_published_at date set before the current government" do
     create(:current_government)
     political_edition = create(:edition, political: true, first_published_at: 10.years.ago)
 
     assert political_edition.valid?
   end
 
+  test "political editions can have their first_published_at date after the earliest change note" do
+    edition_with_change_note = create(:edition_with_document, :published, change_note: "changed", major_change_published_at: 2.days.ago)
+    edition = build(:edition, political: true, document: edition_with_change_note.document, first_published_at: 1.day.ago)
+
+    assert edition.valid?
+  end
+
+  test "historical editions can have their first_published_at date set before the current government" do
+    prev_government = create(:previous_government, start_date: 10.years.ago, end_date: 1.year.ago)
+    create(:current_government, start_date: 1.year.ago)
+    political_edition = create(:edition, political: true, first_published_at: 9.years.ago, government_id: prev_government.id)
+
+    assert political_edition.valid?
+  end
+
+  test "historical editions can have their first_published_at date set after the earliest change note" do
+    prev_government = create(:previous_government, start_date: 10.years.ago, end_date: 1.year.ago)
+    create(:current_government, start_date: 1.year.ago)
+    historic_edition_with_change_note = create(:edition_with_document, :published, change_note: "changed", major_change_published_at: 9.years.ago)
+    historic_edition = create(:edition, political: true, first_published_at: 8.years.ago, government_id: prev_government.id, document: historic_edition_with_change_note.document)
+
+    assert historic_edition.valid?
+  end
+
   test "after_change_notes' error message takes priority if multiple validation errors on first_published_at" do
     edition_with_change_note = create(:edition_with_document, :published, change_note: "changed", major_change_published_at: 2.days.ago)
     edition = build(:edition, document: edition_with_change_note.document, first_published_at: 10.years.from_now)