mosquitto_passwd can't update passwords

[Legion2]

When using mosquitto_passwd to update a password of an existing user the resulting password file is broken and the user can't authenticate to mosquitto with the new password.

Steps to reproduce:

1. create a password file and configure mosquitto to use it
2. add a user mosquitto_passwd -b passwordfile test bla
3. update the user password mosquitto_passwd -b passwordfile test bla2
4. try to connect to the broker with the user "test" and password "bla2"

I'm using the docker image eclipse-mosquitto:1.6.9 for the cli tool and the broker.

[ralight]

Thank you for reporting this, it should now be fixed on the fixes branch.