Verified this bug with latest 4.5 ARM templates, and works.
After installation, check master OSDisk size, it is showing on Azure portal:
Disk Configuration: 1024 GiB (Premium SSD)
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.