py3: fix swift-dispersion-populate

Change-Id: I1f140ae00cbd25b23c9a40ee91dccee8c7c15d81

bin/swift-dispersion-populate

@@ -15,6 +15,7 @@
 # limitations under the License.
 from __future__ import print_function
 
+import io
 import traceback
 from optparse import OptionParser
 from sys import exit, stdout
@@ -22,8 +23,8 @@ from time import time
 
 from eventlet import GreenPool, patcher, sleep
 from eventlet.pools import Pool
+import six
 from six.moves import range
-from six.moves import cStringIO as StringIO
 from six.moves.configparser import ConfigParser
 
 try:
@@ -56,7 +57,8 @@ def put_object(connpool, container, obj, report):
     global retries_done
     try:
         with connpool.item() as conn:
-            conn.put_object(container, obj, StringIO(obj),
+            data = io.BytesIO(obj if six.PY2 else obj.encode('utf8'))
+            conn.put_object(container, obj, data,
                             headers={'x-object-meta-dispersion': obj})
             retries_done += conn.attempts - 1
         if report: