added test for self-reimport at module init time

--HG--
extra : transplant_source : Y%1C%3A%07%2C%60%B0%F0.%EA%B1%23%3F%0E%20%89%13%C5%C24

tests/run/reimport.pyx

+# mode: run
+# tags: import
+
+# reimports at module init time used to be a problem in Py3
+import reimport
+
+def test():
+    """
+    >>> test()
+    True
+    """
+    import sys
+    return reimport in sys.modules.values()