Correct a bug in git parsing.

liquidprompt

@@ -768,7 +768,7 @@ _lp_git_branch_color()
         fi
 
         local shortstat
-        shortstat="$(LANG=C \git diff --shortstat 2>/dev/null)"
+        shortstat="$(LANG=C \git diff --shortstat HEAD 2>/dev/null)"
         if [[ -n "$shortstat" ]] ; then
             local has_lines
             #has_lines=$(\git diff --numstat 2>/dev/null | awk 'NF==3 {plus+=$1; minus+=$2} END {printf("+%d/-%d\n", plus, minus)}')