'extractcode –shallow' returns cryptic error message

Yesterday I ran extractcode (on Ubuntu 16.04, I believe) with a command I composed in LibreOffice, not realizing that the autocorrect feature had converted the double dash `--shallow` into a single emdash or endash (not sure which) `-shallow`. ScanCode returned the following rather cryptic error message:

```
$extractcode –shallow some.zip
Usage: extractcode [OPTIONS]
Try 'extractcode --help' for help on options and arguments.

Traceback (most recent call last):
File "/tmp/scancode-toolkit-develop/bin/extractcode", line 11, in
load_entry_point('scancode-toolkit', 'console_scripts', 'extractcode')()
File "/tmp/scancode-toolkit-develop/local/lib/python2.7/site-packages/click/core.py", line 722, in __call__
return self.main(*args, **kwargs)
File "/tmp/scancode-toolkit-develop/src/scancode/utils.py", line 79, in main
standalone_mode=standalone_mode, **extra)
File "/tmp/scancode-toolkit-develop/local/lib/python2.7/site-packages/click/core.py", line 707, in main
e.show()
File "/tmp/scancode-toolkit-develop/local/lib/python2.7/site-packages/click/exceptions.py", line 48, in show
echo('Error: %s' % self.format_message(), file=file, color=color)
File "/tmp/scancode-toolkit-develop/local/lib/python2.7/site-packages/click/exceptions.py", line 84, in format_message
return 'Invalid value for %s: %s' % (param_hint, self.message)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 6: ordinal not in range(128)
```