Hi,
after a miserable login process I tried to do my first edit with core (latest version). Not very surprisingly, I couldn't. I tried to enter a search-replace pair, then enter to continue. What's wrong?

c:\Pywikibot>pwb replace.py -page:user:BinBot/semmi
Please enter the text that should be replaced: S
Please enter the new text: Q
Please enter another text that should be replaced,
or press Enter to start:
Traceback (most recent call last):
  File "C:\Pywikibot\pwb.py", line 263, in <module>
    if not main():
  File "C:\Pywikibot\pwb.py", line 256, in main
    run_python_file(filename, [filename] + args, argvu, file_package)
  File "C:\Pywikibot\pwb.py", line 121, in run_python_file
    main_mod.__dict__)
  File ".\scripts\replace.py", line 1166, in <module>
    main()
  File ".\scripts\replace.py", line 1023, in main
    ' (-%s +%s)' % (replacement.old, replacement.new)}
  File "C:\Pywikibot\pywikibot\tools\__init__.py", line 1448, in wrapper
    return obj(*__args, **__kw)
  File "C:\Pywikibot\pywikibot\i18n.py", line 621, in twtranslate
    trans = _get_translation(alt, twtitle)
  File "C:\Pywikibot\pywikibot\i18n.py", line 324, in _get_translation
    _messages_package_name, filename).decode('utf-8')
AttributeError: 'NoneType' object has no attribute 'decode'
<class 'AttributeError'>
CRITICAL: Closing network session.

c:\Pywikibot>pwb version.py
Pywikibot: [ssh] pywikibot-core.git (9085b71, g8205, 2017/05/05, 18:08:09, n/a)
Release version: 3.0-dev
requests version: 2.14.2
  cacerts: C:\Program Files\Python36\lib\site-packages\requests\cacert.pem
    certificate test: ok
Python: 3.6.1 (v3.6.1:69c0db5, Mar 21 2017, 18:41:36) [MSC v.1900 64 bit (AMD64)]
PYWIKIBOT2_DIR: Not set
PYWIKIBOT2_DIR_PWB: C:\Pywikibot
PYWIKIBOT2_NO_USER_CONFIG: Not set
Config base dir: c:\Pywikibot