Sums/products of numeric objects should never be held

[kcrisman]

See #9879.

sage: i.mul(2)
2*I
sage: i.mul(2,hold=True)
2*I*
sage: i.mul(2,hold=True).simplify()
2*I
sage: i.mul(i)
-1
sage: i.mul(i,hold=True)
-
sage: i.mul(i,hold=True).simplify()
-1

Component: symbolics

Issue created by migration from https://trac.sagemath.org/ticket/10069

[rwst]

comment:5

I think it's a defect but in the sense that products of numeric objects should never be held. You will find that using the above constructs will cause all sort of problems.

[rwst]

comment:6

However, pynac/pynac#273