Balrogs prefer bullwhip is hero is wielding something

doc/fixes3-7-0.txt

@@ -1254,6 +1254,7 @@ fog clouds maintain any clouds they are in, even poisonous ones
 bone devils summon skeletons
 adjust wand of make invisible and potion of invisibility effects
 barbed devils have an attack that sticks you to them
+balrogs prefer bullwhip if hero is wielding a weapon
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

src/weapon.c

@@ -663,6 +663,8 @@ select_hwep(struct monst *mtmp)
 
     if (is_giant(mtmp->data)) /* giants just love to use clubs */
         Oselect(CLUB);
+    else if (mtmp->data == &mons[PM_BALROG] && uwep)
+        Oselect(BULLWHIP);
 
     /* only strong monsters can wield big (esp. long) weapons */
     /* big weapon is basically the same as bimanual */