upstream::
The name of a local ref which can be considered ``upstream''
from the displayed ref. Respects `:short` in the same way as
- `refname` above.
+ `refname` above. Additionally respects `:track` to show
+ "[ahead N, behind M]" and `:trackshort` to show the terse
+ version: ">" (ahead), "<" (behind), "<>" (ahead and behind),
+ or "=" (in sync). Has no effect if the ref does not have
+ tracking information associated with it.
+
+HEAD::
+ '*' if HEAD matches current ref (the checked out branch), ' '
+ otherwise.
+
+color::
+ Change output color. Followed by `:<colorname>`, where names
+ are described in `color.branch.*`.
In addition to the above, for commit and tag objects, the header
field names (`tree`, `parent`, `object`, `type`, and `tag`) can