Input feature does not work in Python examples that run inside the docker

[eldipa]

Describe the bug
Inside the docker used for testing (make docker-shell), if I run
the docs/basic/input.md examples, Python behaves weird.

$ byexample -l python --ff docs/basic/input.md                                                                                 
File "docs/basic/input.md", line 20                                                                                            
Failed example:                                                                                                                
    name = input("your name please: ")      # byexample: +input                                                                
Expected:                                                                                                                      
your name please: [john]                                                                                                       
Got:                                                                                                                           
your name please: [john]                                                                                                       
Traceback (most recent call last):                                                                                             
  File "<stdin>", line 1, in <module>                                                                                          
  File "<string>", line 1, in <module>                                                                                         
NameError: name 'john' is not defined                                                                                          

The example is:

>>> name = input("your name please: ")      # byexample: +input                                                                
your name please: [john]                                                                                                       

byexample types john so the example does not timeout but
the interpreter then complains the john is not defined like
if we were typing Python code.

This happen only in the docker.

Is the john duplicated somehow and send to input(..) and
to the interpreter?

Is, in somehow, a newline being send before typing john
unblocking input(..) (name would be empty) and when
byexample types john it goes directly to the interpreter?

Expected behavior
The interpreter should never receiver the text sent to the example.

byexample version
byexample 9.1.0 (Python 3.5.3)

[eldipa]

May be docker requires an additional flag, perhaps --tty?