Add context manager test...

handle degenerate 3.8 withas

test/simple_source/stmts/08_test_contextmanager.py

@@ -0,0 +1,21 @@
+"""
+This program is self checking!
+"""
+
+
+class TestContextManager:
+    def __enter__(self):
+        return 1, 2
+
+    def __exit__(self, exc_type, exc_value, exc_tb):
+        return self, exc_type, exc_value, exc_tb
+
+
+with open(__file__) as a:
+    assert a
+
+with open(__file__) as a, open(__file__) as b:
+    assert a.read() == b.read()
+
+with TestContextManager() as a, b:
+    assert (a, b) == (1, 2)