Fix changelog linter to not run indefinitely on invalid changelogs

tools/rail_inspector/lib/rail_inspector/changelog.rb

@@ -155,7 +155,7 @@ def peek_release_header?
 
         def parse_release_header
           @buffer.scan(
-            /#{RELEASE_HEADER} .*##\n\n/o
+            /#{RELEASE_HEADER} .*##\s*/o
           )
         end
 

tools/rail_inspector/test/fixtures/action_mailbox_invalid.md

@@ -0,0 +1,47 @@
+## Rails 7.1.0.rc1 (September 13, 2023) ##
+
+*   No changes.
+
+
+## Rails 7.1.0.beta1 (September 13, 2023) ##
+========
+
+*   Fix `simple_format` with blank `wrapper_tag` option returns plain html tag
+
+    By default `simple_format` method returns the text wrapped with `<p>`. But if we explicitly specify
+    the `wrapper_tag: nil` in the options, it returns the text wrapped with `<></>` tag.
+
+    Before:
+
+    ```ruby
+    simple_format("Hello World", {},  { wrapper_tag: nil })
+    # <>Hello World</>
+    ```
+
+    After:
+
+    ```ruby
+    simple_format("Hello World", {},  { wrapper_tag: nil })
+    # <p>Hello World</p>
+    ```
+
+    *Akhil G Krishnan*, *Junichi Ito*
+
+*   Don't double-encode nested `field_id` and `field_name` index values
+
+    Pass `index: @options` as a default keyword argument to `field_id` and
+    `field_name` view helper methods.
+
+    *Sean Doyle*
+
+*   Allow opting in/out of `Link preload` headers when calling `stylesheet_link_tag` or `javascript_include_tag`
+
+    ```ruby
+    # will exclude header, even if setting is enabled:
+    javascript_include_tag("http://example.com/all.js", preload_links_header: false)
+
+    # will include header, even if setting is disabled:
+    stylesheet_link_tag("http://example.com/all.js", preload_links_header: true)
+    ```
+
+    *Alex Ghiculescu*

tools/rail_inspector/test/rail_inspector/changelog_test.rb

@@ -60,6 +60,15 @@ def test_no_changes_not_treated_as_offense
     assert_equal 0, offenses.length
   end
 
+  def test_invalid_header_does_not_cause_infinite_loop
+    Timeout.timeout(1) do
+      @changelog = changelog_fixture("action_mailbox_invalid.md")
+      assert_equal 2, offenses.length
+    end
+  rescue Timeout::Error
+    flunk "Parsing action_mailbox_invalid.md took too long"
+  end
+
   def test_validate_authors
     assert_offense(<<~CHANGELOG)
       *   Fix issue in CHANGELOG linting