Syslog support in python3 is broken

[Joppie]

Problem

When running supervisord under python3 with a configuration that includes the program option stdout_syslog = true, messages do not show up in syslog.

Versions tested

• 4.0.4
• ff7f181 (latest master at the time)

Debugging

When running supervisord with --nodaemon, exception tracebacks reveal the problem:

Traceback (most recent call last):
  File "/home/staley/.local/lib/python3.7/site-packages/supervisor/loggers.py", line 372, in emit
    for line in message.rstrip('\n').split('\n'):
TypeError: a bytes-like object is required, not 'str'

SyslogHandler.emit is being passed a record that contains a message objects of type bytes not str. Passing str objects into the rstrip and split methods of a byte object is not allowed.

[mnaberez]

Reproduce Instructions

Create a config file supervisord.conf:

[supervisord]

[program:echo]
command = sh -c "echo hello"
stdout_syslog = true 
startsecs = 0
autostart = true
autorestart = false

Start supervisord in the foreground with that config:

$ supervisord -n -c supervisord.conf
2019-10-19 09:32:43,662 INFO supervisord started with pid 6076
2019-10-19 09:32:44,666 INFO spawned: 'echo' with pid 6079
Traceback (most recent call last):
  File ".../supervisor/loggers.py", line 372, in emit
    for line in message.rstrip('\n').split('\n'):
TypeError: a bytes-like object is required, not 'str'
2019-10-19 09:32:44,675 INFO success: echo entered RUNNING state, process has stayed up for > than 0 seconds (startsecs)
2019-10-19 09:32:45,677 INFO exited: echo (exit status 0; expected)

The exception above from line 372 in loggers.py is in SyslogHandler. Tested on Python 2.7 and 3.6. The exception only occurred on Python 3.6.

[mnaberez]

Fixed in #1284.