Substitution in Order fails

[avichaldayal]

O(x**3).subs(x, exp(-x**2)) should be O(exp(-3*x**2), (x, oo))
but gives an error

Related to #7529

[oscarbenjamin]

This still gives an error:

In [12]: O(x**3).subs(x, exp(-x**2))                                                                                                           
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
~/current/sympy/sympy/sympy/core/cache.py in wrapper(*args, **kwargs)
     93                 try:
---> 94                     retval = cfunc(*args, **kwargs)
     95                 except TypeError:

~/current/sympy/sympy/sympy/core/basic.py in _subs(self, old, new, **hints)
   1108 
-> 1109         rv = self._eval_subs(old, new)
   1110         if rv is None:

~/current/sympy/sympy/sympy/series/order.py in _eval_subs(self, old, new)
    442                             sol = set(e1) - set(e2)
--> 443                         res = [dict(zip((d, ), sol))]
    444                         point = d.subs(res[0]).limit(old, self.point[i])

TypeError: zip argument #2 must support iteration

During handling of the above exception, another exception occurred:

TypeError                                 Traceback (most recent call last)
<ipython-input-12-c3379ae81c5e> in <module>
----> 1 O(x**3).subs(x, exp(-x**2))

~/current/sympy/sympy/sympy/core/basic.py in subs(self, *args, **kwargs)
    995             rv = self
    996             for old, new in sequence:
--> 997                 rv = rv._subs(old, new, **kwargs)
    998                 if not isinstance(rv, Basic):
    999                     break

~/current/sympy/sympy/sympy/core/cache.py in wrapper(*args, **kwargs)
     94                     retval = cfunc(*args, **kwargs)
     95                 except TypeError:
---> 96                     retval = func(*args, **kwargs)
     97                 return retval
     98 

~/current/sympy/sympy/sympy/core/basic.py in _subs(self, old, new, **hints)
   1107             return new
   1108 
-> 1109         rv = self._eval_subs(old, new)
   1110         if rv is None:
   1111             rv = fallback(self, old, new)

~/current/sympy/sympy/sympy/series/order.py in _eval_subs(self, old, new)
    441                             e2 = sol.args[1]
    442                             sol = set(e1) - set(e2)
--> 443                         res = [dict(zip((d, ), sol))]
    444                         point = d.subs(res[0]).limit(old, self.point[i])
    445                     newvars[i] = var

TypeError: zip argument #2 must support iteration

[czgdp1807]

The above comment still holds.