problem reported by addi on irc.
this seems to be reachable only on smp,
libdb/db-insert.c use a file lock to avoid opening sample
files by post-profile until an update is in progress in
but we don't protect at all against: the samples file
opened by post profile tools and an update start during
the read by libdb. Ugh
temporary fix is to insert a sleep between op_dump
I'll commit a proper fix, then addi, will test it.
I think it will imply dropping some samples in these rare