When executing a full export
the temporary file "TEMPDIR/config.tar.gz" remains on the server, readable for everyone
michael@michael:/tmp$ ls -l conf* -rw-r--r-- 1 michael www-data 33801 Okt 13 10:12 config.tar.gz -rw-r--r-- 1 michael michael 33801 Okt 13 10:12 config-SITENAME-dev-bk-2015-10-13-08-12.tar.gz
btw. the timestamp of the downloaded file is UTC not localtime. I'm not sure which is the best solution, personally I would prefer a localtimestamp.
The temporary file should be deleted when download has been finished.
Propably the temporary filename should be unique, so that two Drupal8-installation on the same server will not collide
User interface changes