knossosdataset seg.zip file locking broken

[jmrk84]

Under some circumstances, this lock mechanism (which looks very fishy upon superficial inspection, a semaphore is certainly something different) appears to fail, leading to ugly race conditions during knossos dataset writing (line 1928):

                  while True:
                    try:
                        os.makedirs(folder_path+"block")    # Semaphore --------
                        break
                    except:
                        if time.time() - \
                                os.stat(folder_path+"block").st_mtime > 5:
                            os.rmdir(folder_path+"block")
                            os.makedirs(folder_path+"block")
                            break
                        time.sleep(1)`