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On Python 3.4, input() does not use wrapped sys.stdout. For example, the following script should print "Wrapped stdout" by print() and input() because sys.stdout is replaced with Writer object.
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import io
import sys
class Writer:
 def __getattr__(self, name):
 return getattr(sys.__stdout__, name)
 def write(self, data):
 if data != '\n':
 sys.__stdout__.write('Wrapped stdout\n')
 def fileno():
 raise OSError()
sys.stdout = Writer()
print('print')
input('input')
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But the script does not print "Wrapped stdout" as prompt of input(). The script
prints the following.
-----
Wrapped stdout
input
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Although, when sys.stdin is also wrapped, input() will use sys.stdout for prompt. For example, the following script prints "Wrapped stdout" by print() and input().
----
import io
import sys
class Writer:
 def __getattr__(self, name):
 return getattr(sys.__stdout__, name)
 def write(self, data):
 if data != '\n':
 sys.__stdout__.write('Wrapped stdout\n')
 def fileno():
 raise OSError()
class Reader:
 def __getattr__(self, name):
 return getattr(sys.__stdin__, name)
 def read(self, size):
 return sys.__stdin__.read(size)
 def fileno():
 raise OSError()
sys.stdout = Writer()
sys.stdin = Reader()
print('print')
input('input')
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The script prints the following.
-----
Wrapped stdout
Wrapped stdout
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