package mysql-server-5.7 (not installed) failed to install/upgrade: subprocess new pre-installation script returned error exit status 1

$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following additional packages will be installed:
  mysql-server-5.7
Suggested packages:
  mailx tinyca
The following NEW packages will be installed:
  mysql-server-5.7
0 upgraded, 1 newly installed, 0 to remove and 10 not upgraded.
5 not fully installed or removed.
Need to get 0 B/2.584 kB of archives.
After this operation, 48,4 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Preconfiguring packages ...
(Reading database ... 258483 files and directories currently installed.)
Preparing to unpack .../mysql-server-5.7_5.7.12-0ubuntu1_amd64.deb ...
Aborting downgrade from (at least) 10.0 to 5.7.
If are sure you want to downgrade to 5.7, remove the file
/var/lib/mysql/debian-*.flag and try installing again.
dpkg: error processing archive /var/cache/apt/archives/mysql-server-5.7_5.7.12-0ubuntu1_amd64.deb (--unpack):
 subprocess new pre-installation script returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/mysql-server-5.7_5.7.12-0ubuntu1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: mysql-server-5.7 (not installed)
ProcVersionSignature: Ubuntu 4.4.0-22.40-generic 4.4.8
Uname: Linux 4.4.0-22-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
Date: Fri May 27 10:29:51 2016
ErrorMessage: subprocess new pre-installation script returned error exit status 1
InstallationDate: Installed on 2016-05-23 (3 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1.1
 apt 1.2.10ubuntu1
SourcePackage: mysql-5.7
Title: package mysql-server-5.7 (not installed) failed to install/upgrade: subprocess new pre-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)