Comment 40 for bug 1873368

Failure detail:

FROM trusty TO focal python2:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "assembler.py", line 26, in <module>
  File "server.py", line 170, in main
  File "server.py", line 71, in list_routes
  File "server.py", line 51, in _list_routes
  File "ssubprocess.py", line 606, in __init__
  File "ssubprocess.py", line 1117, in _execute_child
OSError: [Errno 2] No such file or directory
client: fatal: server died with error code 1

FROM trusty TO any python3:
  File "<string>", line 1
    import sys; skip_imports=1; verbosity=0; exec compile(sys.stdin.read(764), "assembler.py", "exec")
SyntaxError: invalid syntax

FROM xenial TO focal python2:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "assembler.py", line 36, in <module>
  File "sshuttle.server", line 229, in main
  File "sshuttle.server", line 84, in list_routes
  File "sshuttle.server", line 63, in _list_routes
  File "/usr/lib/python2.7/subprocess.py", line 394, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1047, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory
client: fatal: server died with error code 1

FROM xenial TO trusty python3:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "assembler.py", line 36, in <module>
  File "sshuttle.server", line 243, in main
TypeError: unsupported operand type(s) for %: 'bytes' and 'tuple'
client: fatal: server died with error code 1

FROM xenial TO focal python3:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "assembler.py", line 36, in <module>
  File "sshuttle.server", line 229, in main
  File "sshuttle.server", line 84, in list_routes
  File "sshuttle.server", line 63, in _list_routes
  File "/usr/lib/python3.8/subprocess.py", line 854, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.8/subprocess.py", line 1702, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'netstat'
client: fatal: server died with error code 1

FROM groovy TO any python2:
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "assembler.py", line 18, in <module>
TypeError: module.__init__() argument 1 must be string, not unicode
client: fatal: server died with error code 1