pipenv: Pipenv dockerfile fails to install

Looks like my dockerfiles using pipenv are failing at the moment when I try to build them.

Describe your environment

1. OS Type: Docker pipenv docker file
2. Python version: $ python -V
3. Pipenv version: $ pipenv --version

Expected result

Expected pipenv dockerfile to build and install properly.

Actual result

Docker build fails at pipenv install --deploy --system

 ---> Running in e0eedb80adab
 + pipenv install --deploy --system

Installing dependencies from Pipfile.lock (1c8a85)…
Traceback (most recent call last):
  File "/usr/bin/pipenv", line 11, in <module>
    load_entry_point('pipenv==11.1.4', 'console_scripts', 'pipenv')()
  File "/usr/lib/python3/dist-packages/pipenv/vendor/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/pipenv/vendor/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/usr/lib/python3/dist-packages/pipenv/vendor/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/lib/python3/dist-packages/pipenv/vendor/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/lib/python3/dist-packages/pipenv/vendor/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/pipenv/cli.py", line 197, in install
    selective_upgrade=selective_upgrade
  File "/usr/lib/python3/dist-packages/pipenv/core.py", line 1836, in do_install
    pre=pre, requirements_dir=requirements_directory
  File "/usr/lib/python3/dist-packages/pipenv/core.py", line 1373, in do_init
    requirements_dir=requirements_dir.name)
  File "/usr/lib/python3/dist-packages/pipenv/core.py", line 857, in do_install_dependencies
    requirements_dir=requirements_dir
  File "/usr/lib/python3/dist-packages/pipenv/core.py", line 1474, in pip_install
    c = delegator.run(pip_command, block=block)
  File "/usr/lib/python3/dist-packages/pipenv/vendor/delegator.py", line 267, in run
    c.run(block=block, binary=binary)
  File "/usr/lib/python3/dist-packages/pipenv/vendor/delegator.py", line 156, in run
    s = PopenSpawn(self._popen_args, **pexpect_kwargs)
  File "/usr/lib/python3/dist-packages/pipenv/vendor/pexpect/popen_spawn.py", line 46, in __init__
    self.proc = subprocess.Popen(cmd, **kwargs)
  File "/usr/lib/python3.6/subprocess.py", line 709, in __init__
    restore_signals, start_new_session)
  File "/usr/lib/python3.6/subprocess.py", line 1344, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: '/bin/pip': '/bin/pip'

Steps to replicate

docker build . with a Dockerfile containing

FROM kennethreitz/pipenv