Lost user database after bungled upgrade

Hi everybody,

I lost /etc/master.passwd and friends while trying to recover from an
src upgrade gone wrong.  I'm trying to run "pkg upgrade -f" to get all
of the users and groups created by packages recreating, but pkg is
hitting an assert related to uids:

Checking integrity...Assertion failed: (strcmp(uid, p->uid) != 0),
function pkg_conflicts_check_local_path, file pkg_jobs_conflicts.c,
line 386.

Is there any way to get past this, or is the system toast?