alter table rename missing numeric type

Vince Vielhaber (vev(at)hub(dot)org) reports a bug with a severity of 3
The lower the number the more severe it is.

Short Description
alter table rename missing numeric type

Long Description
I start with table n1 which contains only a numeric type 4,2. Inserting a value larger than 99.99 causes an overflow. Then create a second table which contains only a numeric type 10,2. Values larger than 99.99 insert fine as they should. Renaming table n1 to oldn1 then renaming n2 to n1, attempting to insert a value larger than 99.99 fails. PG is missing the fact that the numeric datatype for the now called table n1 is defined as 10,2.
Subsequently dropping table n1 drops table oldn1! I got bit by this one once on hub.org but didn't notice how I did it, I thought I dropped the wrong table - now I see otherwise.

Sample Code
template1=> create table n1(a numeric(4,2));
CREATE
template1=> insert into n1 values(50.23);
INSERT 360681 1
template1=> insert into n1 values(51.23);
INSERT 360682 1
template1=> insert into n1 values(52.23);
INSERT 360683 1
template1=> insert into n1 values(53.23);
INSERT 360684 1
template1=> insert into n1 values(154.23);
ERROR: overflow on numeric ABS(value) >= 10^2 for field with precision 4 scale 2

template1=> insert into n2 values(154.23);
INSERT 360703 1
template1=> alter table n1 rename to oldn1;
RENAME
template1=> alter table n2 rename to n1;
RENAME
template1=> insert into n1 values(154.23);
ERROR: overflow on numeric ABS(value) >= 10^2 for field with precision 4 scale 2

template1=> \d
Database = template1
+------------------+----------------------------------+----------+
| Owner | Relation | Type |
+------------------+----------------------------------+----------+
| vev | n1 | table |
| vev | oldn1 | table |
+------------------+----------------------------------+----------+

template1=> drop table n1;
DROP
template1=> \d
Database = template1
+------------------+----------------------------------+----------+
| Owner | Relation | Type |
+------------------+----------------------------------+----------+
| vev | n1 | table |
+------------------+----------------------------------+----------+

No file was uploaded with this report