TimedRotatingFileHandler and RotatingFileHandler open new streams in the wrong mode

[nhoad]

TimedRotatingFileHandler and RotatingFileHandler's perform_rollover methods open the new stream in w mode, not a mode. The result is that if multiple processes are writing to logs, then they start competing with each other. Here's some test code that demonstrates:

import logbook
import datetime

log = logbook.Logger("test")
handler = logbook.TimedRotatingFileHandler("testlog.log", date_format='%Y-%m')

with handler:
    log.info("Testing")
    print(handler.stream)
    handler.perform_rollover(handler._get_timestamp(datetime.datetime.utcnow()))
    print(handler.stream)
    log.info("Testing 2")

With the output showing that the mode has changed:

<_io.TextIOWrapper name='/home/nhoad/testlog-2019-10.log' mode='a' encoding='utf-8'>
<_io.TextIOWrapper name='/home/nhoad/testlog-2019-10.log' mode='w' encoding='utf-8'>

Is there a reason that both of these methods not do self._open(self._mode) instead?

[nhoad]

Can I get an update on this? This is causing a lot of issues for me.