Python netmiko wrong output when command character longer than 50

I am trying to use netmiko under windows 10 with python 2.7. When I try to use send_command_set which is including over than 50 character in commands, some special character is including in the output. Because of this wrong output, automation test script is misleading.

Could you let me know how to solve the problem?

(For your information, I am testing DASAN device but since netmiko doesn't support DASAN device, I am using as cisco ios type instead.)

Here is code

from __future__ import absolute_import, division, print_function
import netmiko

output = conn.send_config_set([
    'no service dhcp',
    'service dhcp',
    'ip dhcp option format circuit_id',
    'attr 3 type 0 length-hidden 6 value string 2412533'])

device = {
"device_type": "cisco_ios_telnet",
"ip": "10.47.250.57",
"username": "admin",
"password": ""
}

conn = netmiko.ConnectHandler(**device)
conn.enable()
output = conn.send_config_set(['ip dhcp option format circuit_id',
        'attr 3 type 0 length-hidden 6 value string 2412533'])
print(output)
conn.disconnect()

Here is output including special character ("?[K3" in the end)

config term
SWITCH(config)# ip dhcp option format circuit_id
SWITCH(dhcp-opt[circuit_id])# attr 3 type 0 length-hidden 6 value string 2412533
?[ASWITCH(dhcp-opt[circuit_id])# attr 3 type 0 length-hidden 6 value string 241253?[K3
SWITCH(dhcp-opt[circuit_id])# end
SWITCH#

If I use 49 character instead, it works fine.

config term
SWITCH(config)# ip dhcp option format circuit_id
SWITCH(dhcp-opt[circuit_id])# attr 3 type 0 length-hidden 6 value string 241253
SWITCH(dhcp-opt[circuit_id])# end
SWITCH#