Fix a bug where incoming unicode emails caused logging errors.

The stupid Python stdlib logging module doesn't handle unicode at
all. If debugging is turned on, and SAFELOGGING is disabled, the
incoming emails are logged. If they have any unicode characters,
processing of the emails stops due to UnicodeDecodeErrors.

lib/bridgedb/email/server.py

@@ -174,7 +174,13 @@ class SMTPMessage(object):
         else:
             self.lines.append(line)
         if not safelog.safe_logging:
-            logging.debug("> %s", line.rstrip("\r\n"))
+            try:
+                logging.debug("> %s", line.rstrip("\r\n"))
+            except UnicodeError:  # pragma: no cover
+                pass
+            except Exception as error:  # pragma: no cover
+                logging.error("Error while trying to log incoming email")
+                logging.exception(error)
 
     def eomReceived(self):
         """Tell the :ivar:`responder` to reply when we receive an EOM."""