Bug: psql misquotes constraints

As a result of the constraint output functions being shared between
pg_dump and psql, some of the output is mis-quoted in the display area
for columns including quotes. Notice it's correct in the table Column
list, but the constraint has the escaped versions.

Thoughts?

rt=# create table c ("""vers""ion""" integer unique references a);
NOTICE: CREATE TABLE / UNIQUE will create implicit index
"c_"vers"ion"_key" for table "c"
CREATE TABLE

rt=# \d c
Table "public.c"
Column | Type | Modifiers
------------+---------+-----------
"vers"ion" | integer |
Indexes:
"c_"vers"ion"_key" unique, btree ("""vers""ion""")
Foreign-key constraints:
"$1" FOREIGN KEY ("""vers""ion""") REFERENCES a("version")