Steps to reproduce the issue

1. In admin backend goto System;Global config;Users
2. set Send Password=No

But the password is always sent!

Expected result

The password does not appear in email.

Actual result

The password does appears in email.

System information (as much as possible)

Joomla! 3.6.5 Stable [
OS Linux l
PHP 7.0.7
MySQLi 5.5.5-10.0.29-MariaDB

Additional comments

I assume the bug is in libraries/vendor/joomla/registry/src/
The way class Registry::get() is handling default values.
If sendpassword field in DB is 0, the final check
if (!$found || $node === null || $node === '')
fails since $node=0 and $node === null || $node === '' proably returns true.
In any case that final check is a problem. If the string in the database is set empty $node === ''
for a reason, the default value is returned, which is likely a bug too.