Fix deprecation warning triggered by PEP 479

hy/contrib/sequences.hy

@@ -29,15 +29,15 @@
               (try (while True
                      (yield (get self index))
                      (setv index (inc index)))
-                   (except [_ IndexError]
-                     (raise StopIteration))))
+                   (except [IndexError]
+                     (return))))
    --len-- (fn [self]
              "length of the sequence, dangerous for infinite sequences"
              (setv index (. self high-water))
              (try (while True
                     (get self index)
                     (setv index (inc index)))
-                  (except [_ IndexError]
+                  (except [IndexError]
                     (len (. self cache)))))
    max-items-in-repr 10
    --str-- (fn [self]

hy/core/language.hy

@@ -422,7 +422,10 @@ Raises ValueError for (not (pos? n))."
   (for* [val citer]
     (yield val)
     (for* [_ (range skip)]
-      (next citer))))
+      (try
+        (next citer)
+        (except [StopIteration]
+          (return))))))
 
 (defn zero? [n]
   "Check if `n` equals 0."