Not an absolute MUST, but it SHOULD be used almost always. It helps to track changes and follow the development easier (better commit mail messages and Changelogs are easier to generate).
Please create the commit messages following the git convention:
Think of the first line as of an email "Subject" line. In fact it will be used as "Subject" in the generated commit mails and it will also be used when generating the Changelog (e.g. git log –pretty=oneline). Please start always with the prefix of the subsystem that is modified by the commit (e.g.: "core: typo fixes", "tcp: stun fixes", "mem: faster malloc", "module_name: support for foo", "lib_name: critical bug fix").
Examples:
usrloc: fixed name conflict - destroy_avps() renamed to reg_destroy_avps() to avoid conflicts with the usr_avp.h version.
core: loadpath can now use a list of directories - loadpath can use a list of directories separated by ':', e.g.: loadpath "modules:modules_s:modules_k". First match wins (e.g. for loadmodule "textops" if modules/textops.so or modules/textops/textops.so exists, it will be loaded and the search will stop).
See: