Fixes PlanetUp issue when buying.

If the port has < max holds, and the port sells other things,
it'll offer something else to sell to us.  This fixes that.
It doesn't hang at the "How many hold of" prompt, it answers 0.

flexible.py

@@ -2244,6 +2244,9 @@ class PlanetUpScript(object):
                     self.queue_player.put("T\r")
                     self.state = 8
         elif self.state == 8:
+            if re.match(r"How many holds of .+ do you want to buy \[\d+\]\? ", prompt):
+                # No, no, we're done buying!
+                self.queue_player.put("0\r")
             if re.match(r"Command \[TL=.* \(\?=Help\)\? :", prompt):
                 # Ok, return to the planet...
                 self.queue_player.put("{0}\rE".format(self.planet_sector))