mysqldump will not backup database with --flush-logs parameter and log_error my.cnf parameter defined

If you enabled log_error in my.cnf, eg.

log_error=/var/log/mysql/error.log

and specify mysqldump to backup with the --flush-logs parameter, then mysqldump will not dump anything.
This was tested on a master replication server. After enabling the log_error parameter, mysqldump will not backup anything. After removing the --flush-logs parameter or removing log_error from my.cnf and restarting server, the dump takes place. The full command line used for mysqldump is:

mysqldump -v -F --create-options -e -E -R --master-data=2 --single-transaction -Q -u root --default-character-set=utf8 -p -r db.sql db

As a sidenote, is --flush-logs needed in such a case?