I cannot login into a test clone of my wordpress website

Good day to the community,

I made a clone-copy of all my WP files and folders and created a “test” folder in the root of my host where I copied all those files.
This clone will be used to test new features before applying them to the live site.

I cloned the live database and created a new one, with different name, username and psw (to avoid affecting the live DB when I mess with the test site).
I then copied these database login data to wp-config.php.

I also added to the same file the two lines suggested here:
http://wordpress.org/support/topic/creating-a-duplicate-site-for-testing

Namely:

define('WP_SITEURL', 'http://mydomain.org/test');
define('WP_HOME', 'http://mydomain.org/test');

The original test site was created via a 1-click install provided by my host and it worked, but it became out-of synch with the live one. I have just overwritten those files with the live ones to be sure to have an exact clone.

Now I cannot login to my testsite. Every login attempt is met with a reloaded WP login page with no error message.

I spent a couple of hours trying all workarounds suggested here, to no avail:
http://codex.wordpress.org/Login_Trouble

I also tried the “lost password” link in the login page, but I do not receive any password-reset email.

Thank you for all the help you can give me to get out of this impasse.