#where fails if opts.responds_to?(:==) unexpectedly

Sometimes opts passed in might respond to ==, e.g. `Arel::Nodes::Grouping`. In this case, `opts == :chain` returns `Arel::Nodes::Equality` which causes odd behaviour. Prefer `if :chain == opts` which guarantees that `Symbol#==` would be invoked. Alternatively consider `eql?`.

activerecord/lib/active_record/relation/query_methods.rb

@@ -548,7 +548,7 @@ module ActiveRecord
     # If the condition is any blank-ish object, then #where is a no-op and returns
     # the current relation.
     def where(opts = :chain, *rest)
-      if opts == :chain
+      if :chain == opts
         WhereChain.new(spawn)
       elsif opts.blank?
         self