Proposed resolution:

This wording is relative to N3936.

1. Change [futures.task] p2, class template packaged_task as indicated:

   template <class F>
   explicit packaged_task(F&& f);
   template <class F, class Allocator>
   explicit packaged_task(allocator_arg_t, const Allocator& a, F&& f);
   

2. Change [futures.task.members] as indicated:

   template <class F>
   packaged_task(F&& f);
   template <class F, class Allocator>
   explicit packaged_task(allocator_arg_t, const Allocator& a, F&& f);
   

   […]

   -3- Remarks: These constructors shall not participate in overload resolution if decay_t<F> is the same type as std::packaged_task<R(ArgTypes...)>.

[ 2015-05 Lenexa ]

STL improves proposed wording by restoring the constraint again.

[ 2015-05 Lenexa, SG1 response ]

Back to LWG; not an SG1 issue.

[ 2015-02 Cologne ]

Handed over to SG1.

LWG 2097's resolution was slightly too aggressive. It constrained packaged_task(allocator_arg_t, const Allocator&, F&&), but that's unnecessary because packaged_task doesn't have any other three-argument constructors. Additionally, it's marked as explicit (going back to WP N2798 when packaged_task first appeared) which is unnecessary.