wp-cli/wp-cli — pull request #1532 by danielbachhuber (2014-12-02 00:29:25+00:00)
Title: Persist package file extension in `WP_CLI\CoreUpgrader`

`wp core update` uses ZIP files, while `wp core download` uses gzipped
TAR files. Renaming ZIP files to `.tar.gz` inside of `WP_CLI\CoreUpgrader` causes nasty bugs. Let's keep
them cached separately.

Fixes #1427