pexpect.txt

Title: Attempting to use interact produces TypeError: write() argument must be str, not bytes

The following Python script using `pexpect` connects to the POP3
server `pop3.mailbox.org`. It does not download any email. It will
most likely work on any server.

```python3
#!/usr/bin/python3

# Connection variables: please include your own values
ip = "pop3.mailbox.org"
socket = "995"
user = xxxxxx
password = xxxxxx

import pexpect
import sys

try:
    cmd = f'openssl s_client -connect {ip}:{socket} -quiet'
    child = pexpect.spawn(cmd, timeout=5, encoding='utf-8')
    child.logfile_read = sys.stdout
    child.expect(f'\+OK.*')
    child.sendline(f'user {user}')
    child.expect(f'\+OK.*')
    child.sendline(f'pass {password}')
    child.expect(f'\+OK.*')
    child.interact()
except:
    print("Exception was thrown")
    print("debug information:")
    print(str(child))
    raise
```

Here is the output.

```none
depth=2 C = US, O = DigiCert Inc, OU = www.digicert.com, CN = DigiCert Global Root G2
verify return:1
depth=1 C = US, O = DigiCert Inc, OU = www.digicert.com, CN = Thawte TLS RSA CA G1
verify return:1
depth=0 CN = *.mailbox.org
verify return:1
+OK Dovecot ready.
user xxxxxxxxx
+OK
pass xxxxxxxxx
+OK Logged in.
LIST
+OK 9 messages:
1 134551
2 2599
3 2371
4 3341
5 2539
6 2541
7 2122
8 7185
9 7174
.
```

and I press any key, I get a bunch of diagnostic information from
`print(str(child))`, followed by the following traceback:

```none
Traceback (most recent call last):
  File "/tmp/pexpect.txt", line 31, in <module>
    child.interact()
  File "/usr/lib/python3/dist-packages/pexpect/pty_spawn.py", line 793, in interact
    self.__interact_copy(escape_character, input_filter, output_filter)
  File "/usr/lib/python3/dist-packages/pexpect/pty_spawn.py", line 838, in __interact_copy
    self._log(data, 'read')
  File "/usr/lib/python3/dist-packages/pexpect/spawnbase.py", line 133, in _log
    second_log.write(s)
TypeError: write() argument must be str, not bytes
```

I thought the `encoding='utf-8'` argument to the `spawn` command was
supposed to take care of that issue.