Strange assertion using VACOPT_FREEZE in vacuum.c

Hi all,

When calling vacuum(), there is the following assertion using VACOPT_FREEZE:
Assert((vacstmt->options & VACOPT_VACUUM) ||
    !(vacstmt->options & (VACOPT_FULL | VACOPT_FREEZE)));
I think that this should be changed with sanity checks based on the
parameter values of freeze_* in VacuumStmt as we do not set up
VACOPT_FREEZE when VACUUM is used without options in parenthesis, for
something like that:
        Assert((vacstmt->options & VACOPT_VACUUM) ||
-                  !(vacstmt->options & (VACOPT_FULL | VACOPT_FREEZE)));
+                  ((vacstmt->options & VACOPT_FULL) == 0 &&
+                       vacstmt->freeze_min_age < 0 &&
+                       vacstmt->freeze_table_age < 0 &&
+                       vacstmt->multixact_freeze_min_age < 0 &&
+                       vacstmt->multixact_freeze_table_age < 0));
This would also have the advantage to limit the use of VACOPT_FREEZE
in the query parser.
A patch is attached.
Thoughts?
--
Michael