Roundcube, change password plugin and dovecotpw

I've tried to setup 'change password' plugin in roundcube to use dovecotpw to generate the new user password (hint: Dovecot can use a lot of password schemes). I've configured everything what I thought was relevant. And that was my mistake.

Why?

// Path for dovecotpw (if not in $PATH)
// $rcmail_config['password_dovecotpw'] = '/usr/local/sbin/dovecotpw';

"Great", I thought. "Dovecotpw lies in the $PATH: /usr/sbin/dovecotpw. Nothing to change." But: My $PATH is not the same as the $PATH of my webserver user! D'oh!

After setting the correct path in 'change password' config everything worked as expected.