do not try to launch when there are no pbs files found

launch.py

@@ -418,6 +418,8 @@ class Scheduler:
         self.logfile = logfile
         self.qsub_cmd = qsub_cmd
         self.debug = debug
+        self.search_crit_re = search_crit_re
+        self.path_pbs_files = path_pbs_files
 
     def __call__(self, depend=False):
         """
@@ -485,6 +487,14 @@ class Scheduler:
 
         ii = 0
         ii_max = len(self.pbsflist)
+        if ii_max < 1:
+            print ""
+            print "No files matching %s at:" % self.search_crit_re
+            print self.path_pbs_files
+            print "I have no choice but to abort the launch sequence."
+            print ""
+            return
+
         while True:
             cpu_free, cpu_user = self.check_nodes(self.uid)
             # we only launch a new job when we are not using more than our