apt-get install mysql-server
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 mysql-server : Depends: mysql-server-5.5 but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

grep -v '^#\|^$' /etc/apt/sources.list{,.d/*.list}
/etc/apt/sources.list:deb http://security.debian.org/ jessie/updates main contrib
/etc/apt/sources.list:deb-src http://security.debian.org/ jessie/updates main contrib
/etc/apt/sources.list: deb http://ftp.debian.org/debian/ jessie-updates main contrib non-free
/etc/apt/sources.list: deb-src http://ftp.debian.org/debian/ jessie-updates main contrib non-free
/etc/apt/sources.list: deb http://ftp.debian.org/debian/ jessie main contrib non-free
/etc/apt/sources.list: deb-src http://ftp.debian.org/debian jessie main contrib non-free
/etc/apt/sources.list:
grep: /etc/apt/sources.list.d/*.list: No such file or directory

uname -a
Linux cloud 3.16.0-4-amd64 #1 SMP Debian 3.16.39-1 (2016-12-30) x86_64 GNU/Linux

apt-get -o Debug::pkgProblemResolver=yes dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Starting pkgProblemResolver with broken count: 0
Starting 2 pkgProblemResolver with broken count: 0
Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.