mutt is installed again
Originally created by @sajolida on #15904 (Redmine)
In Tails 3.9 (20180817) `mutt` is installed again.
We removed it from Tails in 1.4.
I could deinstall it from Tails 3.9 with no problem.
Feature Branch: kibi:bugfix/15904-make-sure-mutt-is-not-installed