MySQL 5.7 incompatibility in system upgrade 7061

I'm currently working on updating a Drupal site from 6.38 to 7.59, with a MySQL 5.7.21 DB and PHP 5.3.29.

On running the update script, it fails on update 7061 of the update module, due to a MySQL error: "Error Code: 1171. All parts of a PRIMARY KEY must be NOT NULL; if you need NULL in a key, use UNIQUE instead" in response to "CREATE TABLE system_update_7061 ( `vid` INT DEFAULT NULL, PRIMARY KEY (`vid`) ) ENGINE = InnoDB DEFAULT CHARACTER SET utf8 COMMENT 'Stores temporary data for system_update_7061.'"

I wound up executing the table creation query by hand without the DEFAULT NULL, and was able to complete the update as normal. I dug into this a little bit, and it seems that many contributed modules have resolved this simply by adding a 'not null' => TRUE to the table creation (in this case, at system.install line 2871).

I'm wondering if due to this behavior in MySQL 5.7, if includes/database/mysql/schema.inc (createTableSql, ~ line 92) should instead be modified to automatically add the not null if the field is in the array of primary keys. If so, then I guess this issue component needs to get switched.

I can submit a patch if desired, I just haven't done any Drupal contributions to date (and I'm new to the ecosystem as a whole).