add fix for webpacker:clean command (see rails#2734)

Author: KSJake

.gitignore

@@ -9,3 +9,4 @@ yarn-error.log*
 .yarn-integrity
 /log
 gemfiles/*.lock
+/.idea

lib/webpacker/commands.rb

@@ -23,7 +23,7 @@ def clean(count = 2, age = 3600)
         .each_with_index
         .drop_while do |(mtime, _), index|
           max_age = [0, Time.now - Time.at(mtime)].max
-          max_age < age && index < count
+          max_age < age || index < count
         end
         .each do |(_, files), index|
           files.each do |file|