PCLZIP_ERR_BAD_FORMAT from WP CLI or WGET

When using WP-CLI or wget to download a theme from underscores.me like this:
`wp theme install http://underscores.me/?underscoresme_generate=1&underscoresme_name=SITENAME`
or
`wget -O kansasfpc.zip http://underscores.me/?underscoresme_generate=1&underscoresme_name=SITENAME`

It doesn't work. I get the following error message:
`Warning: The package could not be installed. PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature`

Any thoughts? I was hoping to really automate my jumping-off process, but this is a bit of a hurdle.

Reproduce the failure with the provided WP-CLI and wget commands against the underscores.me generation URL, then inspect the returned download and the archive-generation entry point. Done means the response is a valid ZIP that both commands can install or save without PCLZIP_ERR_BAD_FORMAT.

Written by the indexing model from the issue text.