BUG #14173: Not using partitions with ANY(ARRAY[...])

The following bug has been logged on the website:

Bug reference: 14173
Logged by: Gabriel f
Email address: furstenheim(at)gmail(dot)com
PostgreSQL version: 9.5.2
Operating system: Ubuntu 64bit
Description:

http://stackoverflow.com/questions/34766671/how-to-query-against-several-tables-from-a-partition-in-postgresql

I'm querying a table partitioned wrt to some variable, say mvar. If I do:

explain select * from mtable where mvar = 'a' or mvar = 'b'

then the query planner goes only into the two subtables related to 'a' and
'b'.
The same works with the static in

select * from mtable where mvar IN ('a', 'b')

However, it does not work if I use array

select * from mtable where mvar = ANY(ARRAY['a','b'])

the query planner schedules all subtables of the partition.

I've seen the error both in 9.4 and in 9.5.2. However, according to some
comment in the provided link it did work properly with 9.3

Thanks