Improve gem comment condition

Author: kaukas

railties/CHANGELOG.md

@@ -104,5 +104,9 @@
 
     *Gannon McGibbon*
 
+*   Add support for comments above gem declaration in Rails application templates, e.g. `gem("nokogiri", comment: "For XML")`.
+
+    *Linas Juškevičius*
+
 
 Please check [6-1-stable](https://github.com/rails/rails/blob/6-1-stable/railties/CHANGELOG.md) for previous changes.

railties/lib/rails/generators/actions.rb

@@ -45,7 +45,7 @@ def gem(*args)
 
         in_root do
           str = []
-          unless comment.nil?
+          if comment
             comment.each_line do |comment_line|
               str << indentation
               str << "# #{comment_line}"