fixed multithreading problems when number of worker threads are more than 1
fixed multithreading problems when number of worker threads are more than 1

m13253/pycurl-python3,jcharum/pycurl,ninemoreminutes/pycurl,jcharum/pycurl,m13253/pycurl-python3,ninemoreminutes/pycurl,ninemoreminutes/pycurl,ninemoreminutes/pycurl,jcharum/pycurl,m13253/pycurl-python3