Bug#905873: debootstrap: trusty and xenial not included in merged-usr blacklist

[Randy Goldenberg <randy.goldenberg@ubc.ca>]

Package: debootstrap
Version: 1.0.106
Severity: normal
Tags: patch

Dear Maintainer,

-- System Information:
Debian Release: stretch/sid
  APT prefers xenial-updates
  APT policy: (500, 'xenial-updates'), (500, 'xenial-security'), (500, 'xenial'), (100, 'xenial-backports')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.4.0-131-generic (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

debootstrap 1.0.106 installs a merged-usr file system by default.  Distros that do not use a merged-usr file system are blacklisted in /usr/share/debootstrap/scripts/.  /usr/share/debootstrap/scripts/trusty and /usr/share/debootstrap/scripts/xenial are symlinked to /usr/share/debootstrap/scripts/gutsy.  The script for gutsy does not include trusty and xenial as distros blacklisted for merged-usr file system deployment.  Consequently, merged-usr file systems are set up, resulting in failure when installation of non-merged-usr packages is attempted.  Below please find patch to blacklist trusty and xenial from merged-usr file system deployment.

--- gutsy.a     2018-08-10 14:37:30.569331851 -0700
+++ gutsy.b     2018-08-10 14:32:24.633067670 -0700
@@ -68,7 +68,7 @@ work_out_debs () {
 first_stage_install () {
        case "$CODENAME" in
                # "merged-usr" blacklist for past releases
-               gutsy|hardy|intrepid|jaunty|karmic|lucid|maverick|natty|oneiric|precise|quantal|raring|saucy|utopic|vivid|wily|yakkety|zesty|artful|bionic|cosmic)
+               gutsy|hardy|intrepid|jaunty|karmic|lucid|maverick|natty|oneiric|precise|quantal|raring|saucy|trusty|utopic|vivid|wily|xenial|yakkety|zesty|artful|bionic|cosmic)
                        [ -z "$MERGED_USR" ] && MERGED_USR="no"
                        ;;
                *)