Spaces in environment variables lead to ProcessExecutionError

[gsimbr]

When using environment variables with spaces, the remote machines are unable to execute any command given.

The problem can e.g. reproduced when adapting the unit tests in test_remote.py:

class BaseRemoteMachineTest(object):
    def test_env(self):
        with self._connect() as rem:
            with pytest.raises(ProcessExecutionError):
              rem.python("-c", "import os;os.environ['FOOBAR72']")
            with rem.env(FOOBAR72 = "la la"):
                with rem.env(FOOBAR72 = "baba"):
                    out = rem.python("-c", "import os;print(os.environ['FOOBAR72'])")
                    assert out.strip() == "baba"
                out = rem.python("-c", "import os;print(os.environ['FOOBAR72'])")
                assert out.strip() == "la la"

where I added a space in the "lala" string, which yields

E               plumbum.commands.processes.ProcessExecutionError: Command line: ['cd', '/home/user', '&&', 'env', 'FOOBAR72=la la', '/usr/bin/python', '-c', '"import os;print(os.environ[\'FOOBAR72\'])"']
E               Exit code: 127
E               Stderr:  | env: ‘la’: No such file or directory

The usecase where we stumbled upon this problem was when using the environment variable LDFLAGS="-Wl,-O2 -Wl,--sort-common", which yielded a ProcessExecutionError with any given command:

E               Exit code: 127
E               Stderr:  | env: -Wl,--sort-common: No such file or directory

This is unexpected behaviour and should ideally be fixed by the library by performing appropriate escaping or at least add an earlier check that this is not supported.

[gsimbr]

I should add I've been using plumbum 1.6.7., 1.6.6 is also affected.