BUG #8401: weird input accepted for intervals and geometric types

The following bug has been logged on the website:

Bug reference:      8401
Logged by:          Alexey Borzov
Email address:      borz_off@cs.msu.su
PostgreSQL version: 9.3rc1
Operating system:   irrelevant
Description:

For interval, multiple units:


postgres=# select '1 year day second'::interval;
 interval
----------
 1 year
(1 row)


Geometric, missing comma:


postgres=# select '(1,2)(3,4)'::box, '1,2 3,4'::box;
     box     |     box
-------------+-------------
 (3,4),(1,2) | (3,4),(1,2)
(1 row)


Geometric, one trailing comma:


postgres=# select '(1,2)(3,4),'::box;
     box
-------------
 (3,4),(1,2)
(1 row)


Geometric, more trailing commas:


postgres=# select '(1,2)(3,4)(5,6),,'::path;
        path
---------------------
 ((1,2),(3,4),(5,6))
(1 row)


Geometric, unbalanced delimiters:


postgres=# select '(1,2),3)'::circle;
  circle
-----------
 <(1,2),3>
(1 row)


Geometric, mismatched delimiters:


postgres=# select '((1,2),3>'::circle;
  circle
-----------
 <(1,2),3>
(1 row)


Confirmed on 9.0.13 and 9.3rc1, dates waaaaaay back.