Please read Important note regarding bug reporting.
Yasnippet is part of GNU ELPA, so it falls under the same copyright assignment policy as the rest of Emacs (see "Copyright Assignment" in https://www.gnu.org/software/emacs/CONTRIBUTE). A copyright assignment for Emacs also covers Yasnippet.
The commit message format roughly follows Emacs conventions, although there is no separate Changelog file.
The commit message's first sentence should be capitalized, no period
It may be followed by a paragraph with a longer explanation. The
changelog style entry goes at the end of the message.
* foo.el (a-function): Terse summary of per-function changes.