Steps To Reproduce

sage: A.<x,y> = QQ[]
sage: K = A.fraction_field()
sage: d = { x/y: 0 }
sage: d[K(2*x, 2*y)]
Traceback (most recent call last):
...
KeyError: 2*x/(2*y)

Expected Behavior

(2*x)/(2*y) is equal to x/y, so d[K(2*x, 2*y)] should return 0.

Actual Behavior

The reason why it fails is that x/y and (2*x)/(2*y) differ in their hash though they are considered as equal by equality test.