don't include empty arrays, particularly on scope[:joins] because sco…

…pe[:joins].to_s returns strings like #<ActiveRecord::Relation:0x5021304> breaking the subsequent 'joins.join(" ")'

Signed-off-by: Joel Nimety <jnimety@continuity.net>

lib/acts_as_taggable.rb

@@ -147,8 +147,8 @@ def find_options_for_tag_counts(options = {})
           conditions = conditions.join(" AND ")
 
           joins = ["INNER JOIN #{table_name} ON #{table_name}.#{primary_key} = #{Tagging.table_name}.taggable_id"]
-          joins << options.delete(:joins) if options[:joins]
-          joins << scope[:joins] if scope && scope[:joins]
+          joins << options.delete(:joins) if options[:joins].present?
+          joins << scope[:joins] if scope && scope[:joins].present?
           joins = joins.join(" ")
 
           options = { :conditions => conditions, :joins => joins }.update(options)