How it works...

The get_git_changeset() function takes the absolute_path directory as a parameter and calls the git show shell command with the parameters to show the Unix timestamp of the HEAD revision in the directory. As stated in the previous recipe, we pass BASE_DIR to the function, as we are sure that it is under version control. The timestamp is parsed, converted to a string consisting of year, month, day, hour, minutes, and seconds, returned; and included in the definition of STATIC_URL.