Fix unhashable type error in --selective-upgrade

[alexallah]

The issue

pipenv install PACKAGE_NAME --selective-upgrade crashes with unhashable type: 'list

Traceback (most recent call last):
  File "/usr/local/bin/pipenv", line 11, in <module>
    sys.exit(cli())
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/decorators.py", line 64, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/pipenv/vendor/click/decorators.py", line 17, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/pipenv/cli/command.py", line 249, in install
    editable_packages=state.installstate.editables,
  File "/usr/local/lib/python3.7/site-packages/pipenv/core.py", line 1855, in do_install
    {packages: section[package__name]}, project=project, r=False
TypeError: unhashable type: 'list'

packages variable can not have type list. It looks like we should pass only a package name instead.

The fix

Get the package name and pass it into the function.

[frostming]

Thanks for the catch, a news entry is required and i am good to go.

[alexallah]

Thanks! Added the news file.