BUG #15317: Sort order error

The following bug has been logged on the website:

Bug reference:      15317
Logged by:          sumit pahwa
Email address:      pahwa.sumit@gmail.com
PostgreSQL version: 10.3
Operating system:   Linux
Description:

Version of Postgres deployed
PostgreSQL 10.3 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623
(Red Hat 4.8.5-16), 64-bit

When I execute a query
select 'ALEX DARGAY' >  'ALEXANDER';
It should return false as output because ascii value of space is lower than
ascii value of 'A'.
But the output is true, which is incorrect.
In a bigger picture, It gives a corrupted sorted order.

However, this works fine on PostgreSQL 10.4, compiled by Visual C++ build
1800, 64-bit

Please suggest.

Thanks