The decoration code inside of git returns the decoration type, so
utilize this to create the decoration spans. Additionally, use
prettify_refname(...) to get the shorter name for the ref.
Signed-off-by: Tim Nordell <tim.nordell@logicpd.com>
The decoration span does not need to be emited if there aren't
any decorations to show. This modification saves slightly
on bandwidth.
Signed-off-by: Tim Nordell <tim.nordell@logicpd.com>