Workaround exception caused by incorrect system time (before 1970) reported on IRC by drbobb.

                dataFile = new File(throttleDir, imsiHash);

            }

            // touch the file so it's not LRU

	    if (System.currentTimeMillis() >= 0) {

		dataFile.setLastModified(System.currentTimeMillis());

	    } else {

		// system clock is out of whack, but that doesn't mean we can't boot

		dataFile.setLastModified(Long.MAX_VALUE);

	    }

            checkAndDeleteLRUDataFile(throttleDir);

            return dataFile;

        }