merged r465 from b1.2: fixed #102, Segmentation fault with xcache.var_size=1K
merged r465 from b1.2: fixed #102, Segmentation fault with xcache.var_size=1K

LTD-Beget/xcache,LTD-Beget/xcache,LTD-Beget/xcache,LTD-Beget/xcache,LTD-Beget/xcache