or "=" (in sync). Has no effect if the ref does not have
tracking information associated with it.
+push::
+ The name of a local ref which represents the `@{push}` location
+ for the displayed ref. Respects `:short`, `:track`, and
+ `:trackshort` options as `upstream` does. Produces an empty
+ string if no `@{push}` ref is configured.
+
HEAD::
'*' if HEAD matches current ref (the checked out branch), ' '
otherwise.