fix simulation parameters writting on restart

hysop/simulation.py

@@ -380,13 +380,14 @@ class Simulation(object):
             if ('file' in kwds) and (kwds['file'] is not None):
                 kwds['file'].close()
             if self.mpi_params.rank == io_params.io_leader:
-                if os.path.isfile(filename):
+                if os.path.isfile(filename) and self._restart == 0:
                     os.remove(filename)
                 if (fileformat is IO.ASCII):
                     f = open(filename, 'a')
                     header = '{}\n'.format('\t'.join('{}({})'.format(
                         p.name, p.pretty_name) for p in params))
-                    f.write(header)
+                    if self._restart == 0:
+                        f.write(header)
                     kwds['file'] = f
 
                     formatter = {'float_kind': lambda x: '{:.8g}'.format(x)}