Use Exception.message in copyutil.py only if it exists

Exception.message was removed in Python 3, so only refer to it when it
exists on an Exception instance.

Also fix code style compliance in formatting.py (missing blank lines)

patch by Eduard Tudenhoefner; reviewed by Stefania Alborghetti for CASSANDRA-15702

pylib/cqlshlib/copyutil.py

@@ -146,7 +146,7 @@ class SendingChannel(object):
                     msg = self.pending_messages.get()
                     self.pipe.send(msg)
                 except Exception as e:
-                    printmsg('%s: %s' % (e.__class__.__name__, e.message))
+                    printmsg('%s: %s' % (e.__class__.__name__, e.message if hasattr(e, 'message') else str(e)))
 
         feeding_thread = threading.Thread(target=feed)
         feeding_thread.setDaemon(True)
@@ -1342,7 +1342,7 @@ class FeedingProcess(mp.Process):
         try:
             reader.start()
         except IOError as exc:
-            self.outmsg.send(ImportTaskError(exc.__class__.__name__, exc.message))
+            self.outmsg.send(ImportTaskError(exc.__class__.__name__, exc.message if hasattr(exc, 'message') else str(exc)))
 
         channels = self.worker_channels
         max_pending_chunks = self.max_pending_chunks
@@ -1371,7 +1371,7 @@ class FeedingProcess(mp.Process):
                     if rows:
                         sent += self.send_chunk(ch, rows)
                 except Exception as exc:
-                    self.outmsg.send(ImportTaskError(exc.__class__.__name__, exc.message))
+                    self.outmsg.send(ImportTaskError(exc.__class__.__name__, exc.message if hasattr(exc, 'message') else str(exc)))
 
                 if reader.exhausted:
                     break
@@ -2632,7 +2632,7 @@ class ImportProcess(ChildProcess):
                 pk = get_row_partition_key_values(row)
                 rows_by_ring_pos[get_ring_pos(ring, pk_to_token_value(pk))].append(row)
             except Exception as e:
-                errors[e.message].append(row)
+                errors[e.message if hasattr(e, 'message') else str(e)].append(row)
 
         if errors:
             for msg, rows in errors.items():

pylib/cqlshlib/formatting.py

@@ -239,6 +239,7 @@ def formatter_for(typname):
         return f
     return registrator
 
+
 class BlobType(object):
     def __init__(self, val):
         self.val = val
@@ -246,6 +247,7 @@ class BlobType(object):
     def __str__(self):
         return str(self.val)
 
+
 @formatter_for('BlobType')
 def format_value_blob(val, colormap, **_):
     bval = ensure_text('0x') + ensure_text(binascii.hexlify(val))