- Fix bug MDEV-5919. Was because doing fseek of a stream closed by another thread.

modified:
  storage/connect/filamtxt.cpp

- Fix a bug causing a re-open table not being reset.
modified:
  storage/connect/ha_connect.cc

storage/connect/filamtxt.cpp

@@ -887,6 +887,7 @@ int DOSFAM::RenameTempFile(PGLOBAL g)
   // This loop is necessary because, in case of join,
   // To_File can have been open several times.
   for (PFBLOCK fb = PlgGetUser(g)->Openlist; fb; fb = fb->Next)
+    if (fb == To_Fb || fb == To_Fbt)
       rc = PlugCloseFile(g, fb);
 
   tempname = (char*)To_Fbt->Fname;

storage/connect/ha_connect.cc

@@ -2500,10 +2500,13 @@ int ha_connect::rnd_init(bool scan)
     DBUG_RETURN(HA_ERR_INITIALIZATION);
 
   // Do not close the table if it was opened yet (locked?)
-  if (IsOpened())
+  if (IsOpened()) {
+    if (tdbp->OpenDB(g))      // Rewind table 
+      DBUG_RETURN(HA_ERR_INTERNAL_ERROR);
+    else
       DBUG_RETURN(0);
-//  CloseTable(g);  Was done before making things done twice
-  else if (xp->CheckQuery(valid_query_id))
+
+  } else if (xp->CheckQuery(valid_query_id))
     tdbp= NULL;       // Not valid anymore
 
   // When updating, to avoid skipped update, force the table