Due to the surface tension, the surface of the liquid acts as a stretched membrane. So even if some more water than the rim level of the glass is poured into it, the stretched water surface which holds the glass rim due to adhesion becomes convex upward and the contact angle between the water and the glass becomes more than 90° in this situation.
The zero degrees angle of contact for water and the glass is for the situation when the water level is below the rim level of the glass. In some special situations, the angle of contact may change.