Use unicode_std_stream in nbconvert stdout writer

Closes gh-4578

IPython/nbconvert/writers/stdout.py

@@ -13,6 +13,7 b' Contains Stdout writer'
 # Imports
 #-----------------------------------------------------------------------------
 
+from IPython.utils import io
 from .base import WriterBase
 
 #-----------------------------------------------------------------------------
@@ -30,5 +31,4 b' class StdoutWriter(WriterBase):'
 
         See base for more...
         """
-
-        print(output)
+        io.unicode_std_stream().write(output)

IPython/nbconvert/writers/tests/test_stdout.py

@@ -1,3 +1,4 b''
+# coding: utf-8
 """
 Module with tests for stdout
 """
@@ -43,9 +44,11 b' class TestStdout(TestsBase):'
 
         # Create stdout writer, test output
         writer = StdoutWriter()
-        writer.write('a', {'b': 'c'})
+        writer.write(u'a×', {'b': 'c'})
         output = stream.getvalue()
-        self.fuzzy_compare(output, 'a')
+        if not PY3:
+            output = output.decode('utf-8')
+        self.fuzzy_compare(output, u'a×')
 
         # Revert stdout
         sys.stdout = stdout
  No newline at end of file