9.5: Can't connect with PGSSLMODE=require on Windows

Hi,

With 9.5 alpha 2 on Windows 8 (64-bit), trying to require SSL results
in a blocking error:

pg_hba.conf:
hostssl postgres postgres 0.0.0.0/0 trust

postgresql.conf:
ssl=on

C:\Program Files\PostgreSQL\9.5\bin>SET PGSSLMODE=require

C:\Program Files\PostgreSQL\9.5\bin>psql.exe -p 5432 -U postgres -h
localhost postgres
psql: SSL SYSCALL error: Operation would block (0x00002733/10035)

Doing the same thing on Linux doesn't result in the error (I'm using
latest Git master here):

thom(at)swift:~/Development/data$ PGSSLMODE=require psql -U thom -p 5488
-d postgres -h 127.0.0.1
psql (9.6devel)
SSL connection (protocol: TLSv1.2, cipher:
ECDHE-RSA-AES256-GCM-SHA384, bits: 256, compression: off)
Type "help" for help.

postgres=#

Thom