Traq 4.0 is deprecating support for passwords hashed with sha1, it would be a good idea to display a message to the logged in user asking them to change their password so that it can be switched over to use blowfish.
The plan for this is:
3.6.1 or 3.7.0 will ask if the user wants to change their password.
4.0 will require the user to change their password when they login.
4.1 will display an invalid password for anyone who didn't update their password.