Assertion in zdb?

[Vitalij Satanivskij]

Hello. 

System - 10.0-CURRENT FreeBSD 10.0-CURRENT #2 r255173

While trying to get some statistics from zdb 

 zdb -dd disk1 > stat.log

get some assertion: 

Assertion failed: object_count == usedobjs (0x85727 == 0x3aa93d), file /usr/src/cddl/usr.sbin/zdb/../../../cddl/contrib/opensolaris/cmd/zdb/zdb.c, line 1767.
zsh: abort (core dumped)  zdb -dd disk1 > stat.log

Maybe somebody have any idea about what's it's can be and how big problem it's (or not a problem at all)?