Roll gsutil version to 4.15.

tools/telemetry/third_party/gsutilz/third_party/apitools/apitools/base/py/util_test.py

Index: tools/telemetry/third_party/gsutilz/third_party/apitools/apitools/base/py/util_test.py
diff --git a/tools/telemetry/third_party/gsutilz/third_party/apitools/apitools/base/py/util_test.py b/tools/telemetry/third_party/gsutilz/third_party/apitools/apitools/base/py/util_test.py
index 54dc3e1c389420207674a90ff29cbd0c8a26c0c9..6cb551dd5df0188c0ec6bc0c95c5318b8cb89630 100644
--- a/tools/telemetry/third_party/gsutilz/third_party/apitools/apitools/base/py/util_test.py
+++ b/tools/telemetry/third_party/gsutilz/third_party/apitools/apitools/base/py/util_test.py
@@ -56,14 +56,23 @@ class UtilTest(unittest2.TestCase):
             method_config_no_reserved, {'x': 'foo/:bar:'}))
 
     def testCalculateWaitForRetry(self):
-        self.assertTrue(util.CalculateWaitForRetry(1) in range(1, 4))
-        self.assertTrue(util.CalculateWaitForRetry(2) in range(2, 7))
-        self.assertTrue(util.CalculateWaitForRetry(3) in range(4, 13))
-        self.assertTrue(util.CalculateWaitForRetry(4) in range(8, 25))
-
-        self.assertEquals(10, util.CalculateWaitForRetry(5, max_wait=10))
-
-        self.assertGreater(util.CalculateWaitForRetry(0), 0)
+        try0 = util.CalculateWaitForRetry(0)
+        self.assertTrue(try0 >= 1.0)
+        self.assertTrue(try0 <= 1.5)
+        try1 = util.CalculateWaitForRetry(1)
+        self.assertTrue(try1 >= 1.0)
+        self.assertTrue(try1 <= 3.0)
+        try2 = util.CalculateWaitForRetry(2)
+        self.assertTrue(try2 >= 2.0)
+        self.assertTrue(try2 <= 6.0)
+        try3 = util.CalculateWaitForRetry(3)
+        self.assertTrue(try3 >= 4.0)
+        self.assertTrue(try3 <= 12.0)
+        try4 = util.CalculateWaitForRetry(4)
+        self.assertTrue(try4 >= 8.0)
+        self.assertTrue(try4 <= 24.0)
+
+        self.assertAlmostEqual(10, util.CalculateWaitForRetry(5, max_wait=10))
 
     def testTypecheck(self):