Use BytesIO from io.

jenshnielsen · jenshnielsen · commit 582986b047be · 2015-07-22T17:33:15.000+01:00
Fix bad merge from 8fe495a
diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -17,10 +17,11 @@
 import time
 import warnings
 import zlib
+from io import BytesIO
 
 import numpy as np
 from matplotlib.externals.six import unichr
-from matplotlib.externals.six import BytesIO
+
 
 from datetime import datetime
 from math import ceil, cos, floor, pi, sin
