Debug for 1643147

We need to get the return code _before_ executing the old prompt in
order to not loose the returned value.

liquidprompt.bash

@@ -708,12 +708,12 @@ __sb()
 
 __set_bash_prompt()
 {
-    # execute the old prompt
-    $LP_OLD_PROMPT_COMMAND
-
     # as this get the last returned code, it should be called first
     __RET=$(__sl "$(__return_value $?)")
 
+    # execute the old prompt
+    $LP_OLD_PROMPT_COMMAND
+
     # left of main prompt: space at right
     __JOBS=$(__sr "$(__jobcount_color)")
     __LOAD=$(__sr "$(__load_color)")