convert to print_function

BUG=chromium:414895
TEST=`./cbuildbot/run_tests` passes
TEST=`cros lint` passes (it complains if print is used incorrectly)
TEST=`cbuildbot chromiumos-sdk` passes
TEST=`cbuildbot lumpy-release` passes

Change-Id: I67e7e1290b03a16525e0c2b1afa74ebbd8d3508f
Reviewed-on: https://chromium-review.googlesource.com/218572
Reviewed-by: David James <davidjames@chromium.org>
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/upload_prebuilts_unittest.py b/scripts/upload_prebuilts_unittest.py
index 588a450..ed389c0 100755
--- a/scripts/upload_prebuilts_unittest.py
+++ b/scripts/upload_prebuilts_unittest.py
@@ -5,6 +5,8 @@
 
 """Unittests for upload_prebuilts.py."""
 
+from __future__ import print_function
+
 import copy
 import mox
 import os
@@ -80,10 +82,10 @@
     key = 'PORTAGE_BINHOST'
     value = '1234567'
     prebuilt.UpdateLocalFile(self.version_file, value)
-    print self.version_file
+    print(self.version_file)
     self._read_version_file()
     self._verify_key_pair(key, value)
-    print self.version_file
+    print(self.version_file)
 
   def testUpdateVariable(self):
     """Test updating a variable that already exists."""