resolve problem with DefuncDevice

renew envlist even when not changed
if not, devices in envlist are not exchanged by new instances.

devices.py

@@ -632,8 +632,6 @@ class FrappyConfig(Device):
         to_remove = to_remove.difference(addedenv)
         prevenv = [k for k in session.experiment.envlist if k not in to_remove]
         envlist = prevenv + [k for k in addedenv if k not in prevenv]
-        if set(envlist) == set(prevenv):
-            envlist = None
 
         predef_changes = []
         for aliasname, cfg in predef_aliases:
@@ -644,7 +642,7 @@ class FrappyConfig(Device):
 
     def check_envalias(self):
         envlist, new_aliases, predef_aliases = self.needed_envalias()
-        if envlist:
+        if set(envlist) != set(session.experiment.envlist):
             return f"envlist should be {', '.join(envlist)}"
         anew = [k for k, v in new_aliases.items() if v is not None]
         removed = set(new_aliases).difference(anew)
@@ -695,15 +693,19 @@ class FrappyConfig(Device):
 
             applyAliasConfig()  # for other aliases
 
-        if envlist is not None:
-            prev = session.experiment.envlist
-            removed = set(prev).difference(envlist)
-            session.experiment.setEnvironment(envlist)
-            if removed:
-                session.log.info('removed %s from environment', ', '.join(removed))
-            added = set(envlist).difference(prev)
-            if added:
-                session.log.info('added %s to environment', ', '.join(added))
+        prev = set(session.experiment.envlist)
+        remove = ', '.join(prev.difference(envlist))
+        session.experiment.setEnvironment(envlist)
+        show = []
+        keep = ', '.join(d for d in envlist if d in prev)
+        if keep:
+            show.append(f'keep {keep}')
+        add = ', '.join(d for d in envlist if d not in prev)
+        if add:
+            show.append(f'add {add}')
+        if remove:
+            show.append(f'remove {remove}')
+        session.log.info('environment: %s', '; '.join(show))
 
 
 class FrappyNode(SecNodeDevice, Moveable):