Calendar and tag pages without .html aren't rendered within layout automatically

Expected behaviour

Even if year_link, month_link, day_link and tag_link don't end with .html, their pages are rendered within layout automatically like article pages.

Actual behaviour

These calendar and tag pages are not rendered within layout. If layout: some_layout_name option is specified in their templates, they are rendered within layout.

I guess, article pages inherit blog_options.layout at here, but calendar and tag pages don't. Additionally, pages without .html don't match with extensions_with_layout at here. So explicit layout option is required.

Steps to reproduce the problem

I uploaded a sample project to reproduce it at https://github.com/a2ikm/middleman-blog-test. Its config.rb have chages against default like this:

diff --git a/config.rb b/config.rb
index a373af1..a30c7aa 100644
--- a/config.rb
+++ b/config.rb
@@ -24,16 +24,16 @@
   # This will add a prefix to all links, template references and source paths
   # blog.prefix = "blog"

-  # blog.permalink = "{year}/{month}/{day}/{title}.html"
+  blog.permalink = "{year}/{month}/{day}/{title}"
   # Matcher for blog source files
   # blog.sources = "{year}-{month}-{day}-{title}.html"
-  # blog.taglink = "tags/{tag}.html"
+  blog.taglink = "tags/{tag}"
   # blog.layout = "layout"
   # blog.summary_separator = /(READMORE)/
   # blog.summary_length = 250
-  # blog.year_link = "{year}.html"
-  # blog.month_link = "{year}/{month}.html"
-  # blog.day_link = "{year}/{month}/{day}.html"
+  blog.year_link = "{year}"
+  blog.month_link = "{year}/{month}"
+  blog.day_link = "{year}/{month}/{day}"
   # blog.default_extension = ".markdown"

   blog.tag_template = "tag.html"

Additional information

Ruby version: 2.6.5
Middleman version: 4.3.5
Middleman Blog version: 4.0.3
OS version: OS X 10.14

middleman / middleman-blog