fix(stgit.el): recognize new empty patch marker

In the output of `stg series -e`, the '*' character is now used instead of
'0' to denote empty patches. This change attempts to remain backward
compatible by also still recognizing '0' as the empty patch marker.

Fixes: #342

contrib/stgit.el

@@ -726,7 +726,7 @@ using (make-hash-table :test 'equal)."
  (match-string 0))))
  (while (not (eobp))
  (unless (looking-at
- "\\([0 ]\\)\\([>+-]\\)\\( \\)\\([^ ]+\\) *[|#] \\(.*\\)")
+ "\\([*0 ]\\)\\([>+-]\\)\\( \\)\\([^ ]+\\) *[|#] \\(.*\\)")
  (error "Syntax error in output from stg series"))
  (let* ((state-str (match-string 2))
  (state (cond ((string= state-str ">") 'top)