BUG #8681: column 'n_tup_del' of pg_stat_user_tables doesn't change in case of truncate

The following bug has been logged on the website:

Bug reference:      8681
Logged by:          Anit chakkarwar
Email address:      anitchakkarwar@gmail.com
PostgreSQL version: 9.3.1
Operating system:   Linux
Description:

I came across one issue while truncating table in Postgres9.3, please find
below steps:


First Scenario:


1. Create table and insert some rows.
2. Now delete two rows.
3. If I delete rows 'n_tup_del' column in pg_stat_user_tables is set 2.
4. Do vacuum now i.e vacuum table <tablename>
5. 'n_tup_del' column in pg_stat_user_tables is still showing  2 records.


Second Scenario:


1. Create table and insert some rows.
2. Now truncate table.
3. n_tup_del column in pg_stat_user_tables is 0.


If I do truncate then n_tup_del value is 0 but all the rows are deleted from
table.


Is this something expected behaviour ?