Add a broken test that shows extensions not skipped
Fixed extension filtering in InventoryDirectory
Default use_proxy to True for fetch_url()

Also added some error handling to the fetch_url() call in the
apt_repository module, so that failures to look up the PPA info
are properly handled.

Fixes #7322
Merge pull request #7412 from bellkev/fix_skip_dir_inventory_extensions

Fix skip dir inventory extensions
Also set the environment variables when resetting the locale to C
Don't re-query inventory when trimming failed/dark hosts

Since the filter list contains hosts, passing that back to list_hosts()
in the inventoy causes issues when the hostname is an IPv6 address
(with :'s interpreted as group unions). Since we already have the list
of hosts, we should not need to pass that back through inventory a
second time.

Fixes #7446