Fix #395: Call __exit__ on exception in with block

src/tests/test.py

@@ -0,0 +1,12 @@
+class Test:
+    def __enter__(self):
+        print("enter")
+        return self
+    
+    def __exit__(self, exc_type, exc, tb):
+        print("__exit__ called", exc_type)
+        return False
+
+with Test():
+    print("inside")
+    raise Exception("boom!")