weird error message in sepgsql

I found this in contrib/sepgsql/expected/label.out:

SECURITY LABEL ON COLUMN t2   IS 'system_u:object_r:sepgsql_ro_table_t:s0';   -- be failed
ERROR:  improper relation name (too many dotted names): <nothing>

Contrast with:

SECURITY LABEL ON COLUMN t2.b   IS 'system_u:object_r:sepgsql_ro_table_t:s0';   -- ok

I guess what's happening is that it's calling makeRangeVarFromNameList()
with a list of length zero.

We should either fix the SECURITY LABEL command to catch that case
beforehand, or fix makeRangeVarFromNameList() to give a proper error
message, or both.