Re-use last invoked editor in MH whatnow

This fixes a bug introduced in d30e5a07

* mh/mh.h (mh_whatnow_env) <last_ed>: New member
* mh/mh_whatnow.c (_whatnow): Initialize reedit and last_ed members
Free last_ed before returning
(edit): Prefer wh->last_ed over wh->editor

@@ -210,13 +210,14 @@ struct mh_whatnow_env     /* whatnow shell environment */
   char *file;             /* The file being processed */
   char *msg;              /* File name of the original message (if any) */
   char *draftfile;        /* File to preserve the draft into */
-  const char *editor;
+  const char *editor;     /* Default editor */
   char *prompt;
   char *anno_field;       /* Annotate field to be used */
   mu_list_t anno_list;    /* List of messages (mu_message_t) to annotate */
   mu_mailbox_t mbox;
   int nowhatnowproc;
   int reedit:1;           /* Set if the editor was already invoked */
+  char *last_ed;          /* Last used editor */
 };
 
 #define DISP_QUIT 0

@@ -324,6 +324,9 @@ _whatnow (struct mh_whatnow_env *wh, struct action_tab *tab)
   struct mu_wordsplit ws;
   int wsflags = MU_WRDSF_DEFFLAGS|MU_WRDSF_COMMENT;
 
+  wh->reedit = 0;
+  wh->last_ed = NULL;
+  
   do
     {
       size_t n;
@@ -360,6 +363,8 @@ _whatnow (struct mh_whatnow_env *wh, struct action_tab *tab)
   while (rc == 0);
   if (wsflags & MU_WRDSF_REUSE)
     mu_wordsplit_free (&ws);
+  free (wh->last_ed);
+  wh->last_ed = NULL;
   free (line);
   return status;
 }
@@ -382,8 +387,9 @@ display (struct mh_whatnow_env *wh, int argc, char **argv, int *status)
 static int
 edit (struct mh_whatnow_env *wh, int argc, char **argv, int *whs)
 {
-  char const *ed = wh->editor;
+  char const *ed = wh->last_ed ? wh->last_ed : wh->editor;
   int i, rc, status;
+  char *p;
   
   if (wh->reedit)
     {
@@ -456,7 +462,9 @@ edit (struct mh_whatnow_env *wh, int argc, char **argv, int *whs)
 	mu_error (_("problems with edit"));
     }
 
-  wh->editor = ed;
+  p = mu_strdup (ed);
+  free (wh->last_ed);
+  wh->last_ed = p;
   wh->reedit = 1;
   
   return 0;