Unexpected regression from standard library: AttributeError is thrown when `command` is a list rather than a string

[klardotsh]

While my example below is with Python 3.6 (from Homebrew), I was also able to repro on Python 3.7 (also from Homebrew).

 subprocess.run  » python3
Python 3.6.4 (default, Mar  1 2018, 18:36:50)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)] on darwin
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# First, let's look at the standard library's behavior
>>> import subprocess
>>> subprocess.run('clang')
clang: error: no input files
CompletedProcess(args='clang', returncode=1)
>>> subprocess.run(['clang'])
clang: error: no input files
CompletedProcess(args=['clang'], returncode=1)

# And now for the behavior of this library
>>> import run
>>> run.run('clang')
clang
>>> run.run(['clang'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/joshklar/src/subprocess.run/run/__init__.py", line 146, in __new__
    command, stdin, cwd=cwd, env=env, shell=shell)
  File "/Users/joshklar/src/subprocess.run/run/__init__.py", line 121, in create_process
    shlex.split(command),
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/shlex.py", line 305, in split
    return list(lex)
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/shlex.py", line 295, in __next__
    token = self.get_token()
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/shlex.py", line 105, in get_token
    raw = self.read_token()
  File "/usr/local/Cellar/python/3.6.4_3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/shlex.py", line 136, in read_token
    nextchar = self.instream.read(1)
AttributeError: 'list' object has no attribute 'read'
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