Comment 0 for bug 1812696

From APT src code :

---
* trusty:
apt-1.0.1ubuntu2.18/doc/apt-verbatim.ent:<!ENTITY ubuntu-codename "trusty">

* xenial:
apt-1.2.29/doc/apt-verbatim.ent:<!ENTITY ubuntu-codename "trusty">

* bionic:
apt-1.6.7/doc/apt-verbatim.ent:<!ENTITY ubuntu-codename "xenial">

* disco:
apt-1.8.0~alpha3/doc/apt-verbatim.ent:<!ENTITY ubuntu-codename "xenial">
---

* vendor/ubuntu/sources.list.in
---
# See sources.list(5) manpage for more information
# Remember that CD-ROMs, DVDs and such are managed through the apt-cdrom tool.
deb http://us.archive.ubuntu.com/ubuntu &ubuntu-codename; main restricted
deb-src http://us.archive.ubuntu.com/ubuntu &ubuntu-codename; main restricted

deb http://security.ubuntu.com/ubuntu &ubuntu-codename;-security main restricted
deb-src http://security.ubuntu.com/ubuntu &ubuntu-codename;-security main restricted

deb http://us.archive.ubuntu.com/ubuntu &ubuntu-codename;-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu &ubuntu-codename;-updates main restricted
---

The ubuntu-codename variable for Bionic and late in APT points to Xenial which generate the doc example with Xenial instead of the actual codename.

* ./doc/sources.list.5.xml | grep -i verbatim
---
<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
---

It also seems to affect the man page by mentionning 'xenial' for Bionic:
http://manpages.ubuntu.com/manpages/bionic/man5/sources.list.5.html
http://manpages.ubuntu.com/manpages/bionic/man5/apt_preferences.5.html