PUPMODE 13 with aufs corrupts browser settings and history

[dimkr]

When using aufs, snapmergepuppy copies binary files (like the sqlite database used to store history) to pup_ro1 while the browser writes to them, then deletes them from pup_rw. This means pup_ro1 contains revision x of the file, while the browser is writing revision x+1 to a deleted file. Next time snapmergepuppy runs, the file is missing, so revision x+1 doesn't get copied to pup_ro1 and it's lost.