b4-am SyntaxError on Python 3.5

Hi,

I tried now b4 v0.5.2 on my Ubuntu 16.04 with Python 3.5 and:

  $ b4
  Traceback (most recent call last):
    File "/home/krzk/.local/bin/b4", line 7, in <module>
      from b4.command import cmd
    File "/home/krzk/.local/lib/python3.5/site-packages/b4/__init__.py", line 625
      ecode, out = git_run_command(gitdir, ['show', f'{when}:{fn}'])
                                                                 ^
  SyntaxError: invalid syntax

Is Python v3.5 not supported by b4?

Quoted 13 lines · Krzysztof Kozlowski

Hi,

I tried now b4 v0.5.2 on my Ubuntu 16.04 with Python 3.5 and:

  $ b4
  Traceback (most recent call last):
    File "/home/krzk/.local/bin/b4", line 7, in <module>
      from b4.command import cmd
    File "/home/krzk/.local/lib/python3.5/site-packages/b4/__init__.py", line 625
      ecode, out = git_run_command(gitdir, ['show', f'{when}:{fn}'])
                                                                 ^
  SyntaxError: invalid syntax

Quoted 1 line

Is Python v3.5 not supported by b4?

setup.py specifies that Python 3.6 or above is required.