`kea-admin lease-init mysql` reports key too long

name: Bug report
about: kea-admin

Describe the bug

Running lease-init with MySQL backend produces the following error:

Checking if there is a database initialized already. Please ignore errors.
Initializing database using script ./src/share/database/scripts/mysql/dhcpdb_create.mysql
ERROR 1071 (42000) at line 792: Specified key was too long; max key length is 767 bytes
mysql returned status code 1

Please ignore errors. doesn't help at all either.

To Reproduce

Steps to reproduce the behavior:

1. Run src/bin/admin/kea-admin lease-init mysql -d ./src/share/database/scripts from Kea's root source directory.
2. See error

Expected behavior

All databases should have been created.

Environment:

• Kea version: 1.4.0-git "git 3d0ecb95"
• OS: ArchLinux 1.4
• Which features were compiled in (in particular which backends): --with-mysql --with-pgsql --with-cql
• If/which hooks where loaded in: no hooks

Additional Information

Using MariaDB 10.1.36 database server as a MySQL server, but my guess is this happens for all MySQL servers, maybe only those with InnoDB engine. It seems to be related to the large size of the cummulated VARCHAR sizes per table from the recently added tables.