Since github commit d8146431125eb2e825ca9006298857f7f1c6fb3d the tessera front and back-end code has been split up, which causes some conflicts and changes where the configuration files should go. There is also a missing pip requirement if you want to run tessera with your MySQL backend (ref error: ImportError: No module named MySQLdb)
What to do first? Stop your current tessera inv process. Checkout the latest tessera code and change directory towards it.
Move your custom tessera etc/ config folder to tessera-server/
mv etc/ tessera-server/etc/
Install the MySQL development files in order to build the required Flask-MySQLdb requirement.
sudo yum install mysql-devel
Update the requirements.txt file and include Flask-MySQLdb
echo "Flask-MySQLdb" >> tessera-server/requirements.txt
Time to install the missing pip
cd tessera-server && pip install -r requirements.txt
Update your init.d/tessera startup script and add source env/bin/activate before you run inv run from the tessera-server directory. Afterwards you can run the startup script or start it manually from the CLI (not recommended!!).