joomla/joomla-cms — pull request #1673 by okonomiyaki3000 (2013-08-06 03:55:08+00:00)
Title: When making a new context, base it on the old context.

When creating a new context just to change the user agent, we need to preserve the other settings of the default context. Suppose you are running a site behind a proxy or something, you might have set your default context to deal with that (maybe via a custom plugin) and you won't want this downloader to undo that setting.