dipping acid in a fountain

<Someone> reported that dipping acid in a fountain did not always destroy
the acid.  It might be best to have get_wet call useup in this case, but
that would require more work.

doc/fixes34.4

@@ -18,6 +18,7 @@ grammar of messages regarding eating artifacts
 avoid a message about an invisible monster looking much better
 player polymorphed as a xorn could not pick up items in pits
 don't display "turns to flee" message for a mimicing mimic
+dipping acid in a fountain could cause an explosion but not destroy the potion
 
 
 Platform- and/or Interface-Specific Fixes

src/fountain.c

@@ -391,13 +391,12 @@ register struct obj *obj;
 		if(in_town(u.ux, u.uy))
 		    (void) angry_guards(FALSE);
 		return;
-	} else if (get_wet(obj) && !rn2(2))
+	} else if (get_wet(obj)) {
+	    if (obj->otyp == POT_ACID) { /* Acid and water don't mix */
+		useup(obj);
+		return;
+	    } else if (!rn2(2))		/* no further effect */
 		return;
-
-	/* Acid and water don't mix */
-	if (obj->otyp == POT_ACID) {
-	    useup(obj);
-	    return;
 	}
 
 	switch (rnd(30)) {