Aborted connection NNN to db: 'DB_NAME' user: 'USER' host: 'localhost' (Unknown error)

I open a connection and run a few queries against a DB on localhost. About 571-597 seconds after the connection is established, I get the error:

Sep 25 16:08:20 HOSTNAME mysqld: 150925 16:08:20 [Warning] Aborted connection 126 to db: 'DB_NAME' user: 'USER' host: 'localhost' (Unknown error)

There don't seem to be any variables like '%timeout%' for this much time. The next time the client tries to run a query, I get the error:
oursql.OperationalError: (2006, 'MySQL server has gone away', None)

I don't have a MariaDB development environment setup, but most of the relevant code appears to be in less ./sql/sql_connect.cc.

while (thd_is_connection_alive(thd))

end_connection(thd);

There don't seem to be any other logs around here. There are no other processes, and no queries, running on the mysql server.

Please let me know if I can provide any more information.