suppress gunicorn error which is being caught by errortracker. The

gunicorn error is of this form:

Traceback (most recent call last):
  File "/home/ike/mitx_all/python/local/lib/python2.7/site-packages/gunicorn/workers/sync.py", line 33, in run
    client, addr = self.socket.accept()
  File "/usr/lib/python2.7/socket.py", line 202, in accept
    sock, addr = self._sock.accept()
error: [Errno 11] Resource temporarily unavailable

common/lib/xmodule/xmodule/errortracker.py

@@ -35,6 +35,11 @@ def make_error_tracker():
         if in_exception_handler():
             exc_str = exc_info_to_str(sys.exc_info())
 
+            # don't display irrelevant gunicorn sync error
+            if (('mitx_all/python/local/lib/python2.7/site-packages/gunicorn/workers/sync.py' in exc_str) and
+                ('[Errno 11] Resource temporarily unavailable' in exc_str)):
+                exc_str = ''
+
         errors.append((msg, exc_str))
 
     return ErrorLog(error_tracker, errors)