Fix send and receive of ACK byte in test infrastructure for Python 3.5

[amccarth]

Summary

Python 3.5 is pickier about the distinction between chars and bytes (and strings and bytearrays) than Python 2.7.

The call to ack_bytes.append(chr(42)) was causing a type error to be thrown (during init, so we didn't see a proper stack trace).

I've used the b'*' syntax which creates a bytearray in Python 3 and a plain string in Python 2. I believe this should work in Python 2, but I'm not in a position to test that. If you want to try patching this in to your build to be sure, it would be appreciated.

[tfiala]

LGTM!

lldb/trunk/packages/Python/lldbsuite/test_event/dotest_channels.py

def __init__(self, file_object, async_map, forwarding_func):
             # This whole class is useless if we do nothing with the
             # unpickled results.
             raise Exception("forwarding function must be set")
 
         # Initiate all connections by sending an ack.  This allows
         # the initiators of the socket to await this to ensure
         # that this end is up and running (and therefore already
         # into the async map).
-        ack_bytes = bytearray()
-        ack_bytes.append(chr(42))
+        ack_bytes = b'*'
         file_object.send(ack_bytes)
 
     def deserialize_payload(self):
         """Unpickles the collected input buffer bytes and forwards."""
         if len(self.ibuffer) > 0:
             self.forwarding_func(cPickle.loads(self.ibuffer))
             self.ibuffer = b''
 

lldb/trunk/packages/Python/lldbsuite/test_event/formatter/__init__.py

 class CreatedFormatter(object):
     """Provides transfer object for returns from create_results_formatter()."""
 
     def __init__(self, formatter, cleanup_func):
         self.formatter = formatter
         self.cleanup_func = cleanup_func
 
 
-SOCKET_ACK_BYTE_VALUE = b'*'  # ASCII for chr(42)
-
-
 def create_results_formatter(config):
     """Sets up a test results formatter.
 
     @param config an instance of FormatterConfig
     that indicates how to setup the ResultsFormatter.
 
     @return an instance of CreatedFormatter.
     """
def create_socket(port):
         # This is needed to prevent a race condition
         # in the main dosep.py processing loop: we
         # can't allow a worker queue thread to die
         # that has outstanding messages to a listener
         # socket before the listener socket asyncore
         # listener socket gets spun up; otherwise,
         # we lose the test result info.
         read_bytes = sock.recv(1)
-        if read_bytes is None or (len(read_bytes) < 1) or (read_bytes[0] != SOCKET_ACK_BYTE_VALUE):
+        if read_bytes is None or (len(read_bytes) < 1) or (read_bytes != b'*'):
             raise Exception("listening socket did not respond with ack byte: response={}".format(read_bytes))
 
         return sock, lambda: socket_closer(sock)
 
     default_formatter_name = None
     results_file_object = None
     cleanup_func = None