This bug was fixed in the package debootstrap - 1.0.78+nmu1ubuntu1.6
--------------- debootstrap (1.0.78+nmu1ubuntu1.6) xenial; urgency=medium
* Add (Ubuntu) cosmic as a symlink to gutsy. (LP: #1773496)
-- Steve Langasek <email address hidden> Fri, 25 May 2018 23:56:14 -0700
This bug was fixed in the package debootstrap - 1.0.78+ nmu1ubuntu1. 6
--------------- nmu1ubuntu1. 6) xenial; urgency=medium
debootstrap (1.0.78+
* Add (Ubuntu) cosmic as a symlink to gutsy. (LP: #1773496)
-- Steve Langasek <email address hidden> Fri, 25 May 2018 23:56:14 -0700