core download --no-extract names the archive after a temporary file #354

When wp core download --no-extract downloads an archive that is not in the WP-CLI cache yet, the archive is saved under the name of the temporary download file, such as wp_aB3dEf.zip, instead of wordpress-<version>-<locale>.zip. Only when the archive comes from the cache does it get the expected name.

The scenario "Core download with no-extract should not unzip the download file" in features/core-download.feature only passes because the scenario before it puts the same archive in the cache. Run on its own, with an empty cache, it fails. This also makes it fail in parallel test runs (wp-cli/wp-cli-tests#390).

The archive should get the same name whether it was downloaded or taken from the cache.