Variable: vc-git-root-log-format

Git log format for `vc-print-root-log'.
This should be a list (FORMAT REGEXP KEYWORDS), where FORMAT is a
format string (which is passed to "git log" via the argument
"--pretty=tformat:FORMAT"), REGEXP is a regular expression
matching the resulting Git log output, and KEYWORDS is a list of
`font-lock-keywords' for highlighting the Log View buffer.