Sync fails with offlineimap-7.1.0

[Andreas Fink]

Hello,
I upgraded today in the morning to version 7.1.0 and could not sync anymore. The error I
get is:
OfflineIMAP 7.1.0
  Licensed under the GNU GPL v2 or any later version (with an OpenSSL exception)
*** Processing account gmail
Establishing connection to imap.googlemail.com:993 (gmailremote)
ERROR: While attempting to sync account 'gmail'
  IMAP4 protocol error: program error: <class 'TypeError'> - can't use a bytes pattern on a string-like object
*** Finished account 'gmail' in 0:00
ERROR: Exceptions occurred during the run!
ERROR: While attempting to sync account 'gmail'
  IMAP4 protocol error: program error: <class 'TypeError'> - can't use a bytes pattern on a string-like object

Traceback:
  File "/usr/lib64/python3.4/site-packages/offlineimap/accounts.py", line 281, in syncrunner
    self.__sync()
  File "/usr/lib64/python3.4/site-packages/offlineimap/accounts.py", line 344, in __sync
    remoterepos.getfolders()
  File "/usr/lib64/python3.4/site-packages/offlineimap/repository/IMAP.py", line 452, in getfolders
    imapobj = self.imapserver.acquireconnection()
  File "/usr/lib64/python3.4/site-packages/offlineimap/imapserver.py", line 542, in acquireconnection
    af=self.af,
  File "/usr/lib64/python3.4/site-packages/offlineimap/imaplibutil.py", line 194, in __init__
    super(WrappedIMAP4_SSL, self).__init__(*args, **kwargs)
  File "/usr/lib64/python3.4/site-packages/offlineimap/bundled_imaplib2.py", line 2183, in __init__
    IMAP4.__init__(self, host, port, debug, debug_file, identifier, timeout, debug_buf_lvl)
  File "/usr/lib64/python3.4/site-packages/offlineimap/bundled_imaplib2.py", line 400, in __init__
    self.welcome = self._request_push(name='welcome', tag='continuation').get_response('IMAP4 protocol error: %s')[1]
  File "/usr/lib64/python3.4/site-packages/offlineimap/bundled_imaplib2.py", line 201, in get_response
    raise typ(exc_fmt % str(val))


I tried downgrading to 7.0.14 again, but I get the same error with that version now. I
have no clue what happened here. I did a system update today, so it can also be a python
package that offlineimap depends on (most probably this is the root cause, because 7.0.14
does not work now).

Any hints where to look first?
Cheers
Andreas