Correct super call in HookMetaPaths.__setitem__

Fixes #2

Also added a test.

importhook/meta_paths.py

@@ -12,4 +12,4 @@ class HookMetaPaths(list):
         super(HookMetaPaths, self).__init__([hook_finder(f) for f in finders])
 
     def __setitem__(self, key, val):
-        super(HookMetaPaths, self).__setitem__(hook_finder(val))
+        super(HookMetaPaths, self).__setitem__(key, hook_finder(val))

importhook/tests/test_meta_paths.py

@@ -0,0 +1,15 @@
+from importhook import HookMetaPaths
+
+
+class DummyFinder:
+    pass
+
+
+def test_hook_meta_paths_setitem():
+    finder1 = DummyFinder()
+    finder2 = DummyFinder()
+    paths = HookMetaPaths([finder1, finder2])
+    finder3 = DummyFinder()
+    paths[0] = finder3
+    assert paths == [finder3, finder2]
+    assert finder3.__hooked__ is True