Problem:

After upgrading from MySQL 5.6, a MySQL 5.7 slave is not handling
replication channels correctly.

Analysis:

The upgrade procedure is inverting the order of two fields of the
mysql.slave_master_info table (Channel_Name and Tls_version).

Fix:

Asserted the correct position of the Channel_Name field at
mysql.slave_master_info table while upgrading.

Added a verification to the master_info table repository expecting
that the table primary key field (Channel_name) is at the correct
column, otherwise it will fail to initialize the repository.