[svn r38427] significantly reducing the trailing "Exception in Thread"

messages by having threads die more silently.  Most
of these threads and tracebacks are anyway on some
remote machine, and we need to take care that errors
are routed to the place of invocation (e.g. the
remote_exec() invoker should get remote exceptions,
if the remote thread goes out of scope, the resulting
exception will not be seen likely, anyway)

--HG--
branch : trunk

py/execnet/gateway.py

@@ -104,7 +104,7 @@ class Gateway(object):
                     self._trace("received <- %r" % msg)
                     msg.received(self)
                 except sysex:
-                    raise
+                    break
                 except EOFError:
                     break
                 except:
@@ -131,7 +131,7 @@ class Gateway(object):
                     self._traceex(excinfo)
                     if msg is not None:
                         msg.post_sent(self, excinfo)
-                    raise
+                    break
                 else:
                     self._trace('sent -> %r' % msg)
                     msg.post_sent(self)
@@ -167,7 +167,7 @@ class Gateway(object):
                 close() 
                 self._trace("execution finished:", repr(source)[:50])
         except (KeyboardInterrupt, SystemExit):
-            raise
+            pass 
         except:
             excinfo = exc_info()
             l = traceback.format_exception(*excinfo)