Relation#merge should not lose readonly(false) flag.

The original code ignores the `false` value because `false.blank? # => true`.

1 files changed, 5 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/relation/merger.rb b/activerecord/lib/active_record/relation/merger.rb
index 530c47d0d0..c05632e688 100644
--- a/activerecord/lib/active_record/relation/merger.rb
+++ b/activerecord/lib/active_record/relation/merger.rb
@@ -58,7 +58,11 @@ module ActiveRecord
       def merge
         normal_values.each do |name|
           value = values[name]
-          relation.send("#{name}!", *value) unless value.blank?
+          # The unless clause is here mostly for performance reasons (since the `send` call might be moderately
+          # expensive), most of the time the value is going to be `nil` or `.blank?`, the only catch is that
+          # `false.blank?` returns `true`, so there needs to be an extra check so that explicit `false` values
+          # don't fall through the cracks.
+          relation.send("#{name}!", *value) unless value.nil? || (value.blank? && false != value)
         end
 
         merge_multi_values