dochugw(mon, X)

Reverse the sense of dochugw()'s new 'X' argument. Use True for the
usual case and False for the special case rather than the other way
around.

Call the special case variant when a monster teleports so that hero
stops occupation if the monster jumps to a position where it becomes
a threat.

src/monmove.c

@@ -113,14 +113,15 @@ watch_on_duty(register struct monst* mtmp)
 int
 dochugw(
     register struct monst *mtmp,
-    boolean dontchug) /* True: monster was just created, or maybe it has
-                       * teleported; perform stop-what-you're-doing-if-close-
-                       * enough-to-be-a-threat check but don't move mtmp */
+    boolean chug) /* True: monster is moving;
+                   * False: monster was just created or has teleported
+                   * so perform stop-what-you're-doing-if-close-enough-
+                   * to-be-a-threat check but don't move mtmp */
 {
-    int x = mtmp->mx, y = mtmp->my;
-    boolean already_saw_mon = ((dontchug || !g.occupation) ? 0
-                               : canspotmon(mtmp));
-    int rd = dontchug ? 0 : dochug(mtmp);
+    int x = mtmp->mx, y = mtmp->my; /* 'mtmp's location before dochug() */
+    /* skip canspotmon() if occupation is Null */
+    boolean already_saw_mon = (chug && g.occupation) ? canspotmon(mtmp) : 0;
+    int rd = chug ? dochug(mtmp) : 0;
 
     /*
      * A similar check is in monster_nearby() in hack.c.