This package is a vendor widely used by sgtk to parse configuration files
in YAML format.
This package is shipped in source format, that means that only *.py are
included in python/tank_vendor/yaml for python versions 2.7 and 3.
If you need to upgrade this package you can use the script upgrade_pyyaml.py.
cd tk-core/developer
python upgrade_pyyaml.py