Fix ball bypass sanity complaint

Be punished, get swallowed, drop the ball inside the monster
via the 'D' drop, kill the swallower - this issued a sanity
check complaint about the ball bypass flag.

In this case, the ball was "floating", not on any object chain,
when dropped inside the monster, so clear_bypasses didn't
clear the flag.

src/worn.c

@@ -839,6 +839,11 @@ clear_bypasses(void)
         /* no MCORPSENM(mtmp)==PM_LONG_WORM check here; long worms can't
            be just created by polymorph and migrating at the same time */
     }
+
+    /* ball can be "floating", not on any chain */
+    if (uball)
+        uball->bypass = 0;
+
     /* g.billobjs and g.mydogs chains don't matter here */
     g.context.bypasses = FALSE;
 }