Resume prelu_test in python2

Author: velconia

python/paddle/fluid/tests/unittests/test_prelu_op.py

@@ -16,6 +16,7 @@
 
 import unittest
 import numpy as np
+import six
 from op_test import OpTest
 
 
@@ -62,17 +63,20 @@ def test_check_grad_3_ignore_alpha(self):
 
 
 # TODO(minqiyang): Resume these test cases after fixing Python3 CI job issues
-#  class TestCase1(PReluTest):
-#  def initTestCase(self):
-#  self.attrs = {'mode': "all"}
+if six.PY2:
 
-#  class TestCase2(PReluTest):
-#  def initTestCase(self):
-#  self.attrs = {'mode': "channel"}
+    class TestCase1(PReluTest):
+        def initTestCase(self):
+            self.attrs = {'mode': "all"}
+
+    class TestCase2(PReluTest):
+        def initTestCase(self):
+            self.attrs = {'mode': "channel"}
+
+    class TestCase3(PReluTest):
+        def initTestCase(self):
+            self.attrs = {'mode': "element"}
 
-#  class TestCase3(PReluTest):
-#  def initTestCase(self):
-#  self.attrs = {'mode': "element"}
 
 if __name__ == "__main__":
     unittest.main()