Do Ghasts spawn near portals in the overworld?

From the Minecraft Wiki

Notch added a small chance for Ghasts to spawn in the Overworld near Portals in Beta 1.5. A Ghast spawned outside of the Nether will fly everywhere, mainly above the clouds. Can even spawn extremely rarely without a portal.

Notch's actual confirmation

This is my understanding of the situation:

• Notch planned to have ghasts spawning near portals, before the Halloween update.
• It was not actually implemented in the Halloween update or any later one.

I believe the latter has been found to be the case by those who have studied the code of Minecraft, but I don't have a citation handy. Minecraft Forums would be the place to look for one.