Comment 2 for bug 1325708

StacktraceTop:
 ped_assert (cond_text=cond_text@entry=0x7fa23e256d6c "!dev->external_mode", file=file@entry=0x7fa23e256d39 "../../libparted/device.c", line=line@entry=378, function=function@entry=0x7fa23e256de0 <__PRETTY_FUNCTION__.5821> "ped_device_sync") at ../../libparted/debug.c:112
 ped_device_sync (dev=<optimized out>) at ../../libparted/device.c:378
 ped_geometry_sync (geom=<optimized out>) at ../../libparted/cs/geom.c:340
 fat_write_sync_fragments (fs=0x15cdfe0, buf=<optimized out>, frag=<optimized out>, count=count@entry=1) at ../../../../libparted/fs/fat/fatio.c:78
 fat_write_sync_fragment (fs=<optimized out>, buf=<optimized out>, frag=<optimized out>) at ../../../../libparted/fs/fat/fatio.c:86