Fresh initdb contains a few deleted B-Tree pages

I would like to put on the record that there are a few deleted B-Tree
pages in a freshly initdb'd database. As my btreecheck tools shows:

mgd=# select bt_index_verify(indexrelid::regclass::text) from pg_index;
NOTICE:  00000: page 12 of index "pg_attribute_relid_attnam_index" is deleted
LOCATION:  bt_page_verify_worker, btreecheck.c:206
NOTICE:  00000: page 13 of index "pg_attribute_relid_attnam_index" is deleted
LOCATION:  bt_page_verify_worker, btreecheck.c:206
NOTICE:  00000: page 14 of index "pg_attribute_relid_attnam_index" is deleted
LOCATION:  bt_page_verify_worker, btreecheck.c:206
NOTICE:  00000: page 9 of index "pg_attribute_relid_attnum_index" is deleted
LOCATION:  bt_page_verify_worker, btreecheck.c:206

(contrib/pageinspect's bt_page_items() will show a similar message if
this is done manually)

This is not a new-to-9.4 issue. I am not suggesting that it's a real
problem that requires immediate fixing, but it is suboptimal. We may
wish to fix this someday.

-- 
Peter Geoghegan