treat single instance of seweb / sehistory properly

there is only one seweb / sehistory instance.
care has to be taken as the instrument is not part of the command

base.py

@@ -84,6 +84,7 @@ class ServiceManager:
     revcmd = {}
     USAGE = None
     main_ins = None
+    single_ins = None
 
     def __init__(self):
         self.env = {}
@@ -154,6 +155,8 @@ class ServiceManager:
                 if cmd.startswith('PY '):
                     cmd = env.get('PY', 'python3') + cmd[2:]
                 self.commands[ins] = cmd
+        if len(self.info) == 1:
+            self.single_ins = list(self.info)[0]
         self.info = result
 
     #def get_cmdpats(self, groups):
@@ -210,7 +213,7 @@ class ServiceManager:
                     match = cmdpat.match(cmd)
                     if match:
                         gdict = match.groupdict()
-                        ins = gdict.get('ins', self.main_ins)
+                        ins = gdict.get('ins', self.main_ins) or self.single_ins
                         serv = gdict.get('serv', '')
                         if cfginfo is not None and 'cfg' in gdict:
                             cfginfo[ins, serv] = gdict['cfg']
@@ -430,6 +433,7 @@ class ServiceManager:
 
     def do_list(self, ins=None, *args):
         """info about running services"""
+        self.get_info()
         show_unused = ins == 'all'
         if show_unused:
             ins = None