Jun Wu <quark@fb.com> [Wed, 10 Feb 2016 16:59:34 +0000] rev 28155
extensions: add notloaded method to return extensions failed to load
Before this patch, there is no easy way to detect if there are extensions
failed to load. While this is okay for most situations, chgserver is designed
to preload all extensions specified in config and does need the information.
This patch adds extensions.notloaded() to return names of extensions failed
to load.