pysiril 0.0.12 problem with 1.2-betta1

Downloaded 1.2-betta1 and pysiril (0.0.12) completely stopped to work:

  app=Siril()
  cmd=Wrapper(app)
WARNING: pysiril uses by default :C:/Program Files/SiriL/bin/siril.exe
INFO   : VERSION siril 1.2.0-beta1 :
INFO   : Siril is compatible with pysiril
INFO   : Initialisation pySiril V0.0.12 : OK
INFO   : First step: Starting 'Siril -p' ....
INFO   : ThreadSiril is started
INFO   : run : C:/Program Files/SiriL/bin/siril.exe -p
INFO   : waiting:
7s
INFO   : Second step: Starting pipe reader ....
INFO   : ThreadReader is started
INFO   : Third step: Starting pipe writer ....
ERROR  : *** ThreadReader::run() 'str' object has no attribute 'append'

With 1.0.6 the same worked well:

WARNING: pysiril uses by default :C:/Program Files/SiriL/bin/siril.exe
INFO   : VERSION siril 1.0.6 :
INFO   : Siril is compatible with pysiril
INFO   : Initialisation pySiril V0.0.12 : OK
INFO   : First step: Starting 'Siril -p' ....
INFO   : ThreadSiril is started
INFO   : run : C:/Program Files/SiriL/bin/siril.exe -p
INFO   : waiting:
7s
INFO   : Second step: Starting pipe reader ....
INFO   : ThreadReader is started
INFO   : Third step: Starting pipe writer ....
INFO   : PipeWriter is started
INFO   : Open()

What can be wrong?