add regression test for select timeout bug

greentest/test__select.py

+from time import time
+from gevent import select
+import greentest
+
+
+class TestSelect(greentest.TestCase):
+
+    def test_timeout(self):
+        start = time()
+        select.select([], [], [], 0.1)
+        delay = time() - start
+        assert 0.1 - 0.02 < delay < 0.1 + 0.02, delay
+
+
+if __name__=='__main__':
+    greentest.main()