Fixed a bug in mul_heap.
Fixed a bug in mul_heap.

fredrik-johansson/flint2,fredrik-johansson/flint2,jpflori/flint2,jpflori/flint2,jpflori/flint2,dsroche/flint2,wbhart/flint2,dsroche/flint2,jpflori/flint2,dsroche/flint2,wbhart/flint2,fredrik-johansson/flint2,wbhart/flint2,dsroche/flint2