Fix hash comparison for internal test

Change-Id: Iaf177e98ec6f13c19cd62f02bfe3915ba8c5e25f
diff --git a/tools/utils.py b/tools/utils.py
index eb7849b..9dc1147 100644
--- a/tools/utils.py
+++ b/tools/utils.py
@@ -365,7 +365,7 @@
   cmd = [get_gsutil(), 'cat', destination]
   PrintCmd(cmd)
   try:
-    return subprocess.check_output(cmd)
+    return str(subprocess.check_output(cmd))
   except subprocess.CalledProcessError as e:
     if ignore_errors:
       return ''