over calling change callbacks which are unnecessary.

middleman-core/lib/middleman-core/sitemap/store.rb

@@ -146,9 +146,9 @@ module Middleman
       # Get the URL path for an on-disk file
       # @param [String] file
       # @return [String]
-      Contract IsA['Middleman::SourceFile'] => String
+      Contract Or[Pathname, IsA['Middleman::SourceFile']] => String
       def file_to_path(file)
-        relative_path = file[:relative_path].to_s
+        relative_path = file.is_a?(Pathname) ? file.to_s : file[:relative_path].to_s
 
         # Replace a file name containing automatic_directory_matcher with a folder
         unless @app.config[:automatic_directory_matcher].nil?

middleman-core/lib/middleman-core/sources.rb

@@ -339,7 +339,7 @@ module Middleman
           valid_updated = updated_files.select { |f| f[:types].include?(callback[:type]) }
           valid_removed = removed_files.select { |f| f[:types].include?(callback[:type]) }
 
-          callback[:proc].call(valid_updated, valid_removed)
+          callback[:proc].call(valid_updated, valid_removed) unless valid_updated.empty? && valid_removed.empty?
         end
       end
     end

middleman-core/lib/middleman-core/version.rb

@@ -1,5 +1,5 @@
 module Middleman
   # Current Version
   # @return [String]
-  VERSION = '4.0.0.alpha.4' unless const_defined?(:VERSION)
+  VERSION = '4.0.0.alpha.5' unless const_defined?(:VERSION)
 end