When logout by clicking logout button on the top of /user/modify-profile link, you will be redirected to the login page.
But if you login immediately then you will get the login page again and loop.
It is caused by an address checking error. Now try to fix.
In order to support PHP7, change the way to operate database. PHP7
removed the mysql extension, so the old way to operate database is
not usable. This commit use a new way to operate database.
BREAKING CHANGE: the way to operate database has changed.