'DynamicConversationTab' object has no attribute 'key_func'

Steps to reproduce

• ???

Observed behaviour

2019-08-24 21:06:17,127 DEBUG:core:Input is readable.                                          
2019-08-24 21:06:17,127 DEBUG:core:Got from keyboard: (['^M'],)                                
2019-08-24 21:06:17,127 ERROR:base_events:Exception in callback Core.on_input_readable()       
handle: <Handle Core.on_input_readable()>                                                      
Traceback (most recent call last):                                                             
  File "/usr/lib/python3.7/asyncio/events.py", line 88, in _run                                
    self._context.run(self._callback, *self._args)                                             
  File "/usr/lib/python3.7/site-packages/poezio/core/core.py", line 617, in on_input_readable  
    self.do_command(replace_line_breaks(char), False)                                          
  File "/usr/lib/python3.7/site-packages/poezio/core/core.py", line 776, in do_command         
    self.tabs.current_tab.on_input(key, raw)                                                   
  File "/usr/lib/python3.7/site-packages/poezio/tabs/conversationtab.py", line 291, in on_input
    if not raw and key in self.key_func:                                                       
AttributeError: 'DynamicConversationTab' object has no attribute 'key_func'