ID 310306 - VectorDistort's "Premult" option does not work.

Problem summary
When you select the "Premult" option in the VectorDistort node the pre-multiplication is not applied.

Customer reported version
nuke.10.5v5

Customer reported platform
centos7

Steps to reproduce

1) Launch NukeX 10.0v1 and above.

2) Paste the following expression into Nuke:

set cut_paste_input [stack 0]
version 10.5 v1
CheckerBoard2 {
 inputs 0
 format "3414 2198 0 0 3414 2198 1 "
 name CheckerBoard2
 selected true
 xpos -489
 ypos -101
}
Radial {
 output alpha
 replace true
 area {856 550 2568 1651}
 plinear true
 name Radial2
 selected true
 xpos -489
 ypos -29
}
set N82d4340 [stack 0]
push $N82d4340
Dot {
 name Dot1
 selected true
 xpos -581
 ypos -19
}
SmartVector {
 file /media/TICKET_DATA/28310/test_%04d.exr
 render_range custom
 file.first_frame 1
 file.last_frame 100
 render_root_frame 1
 name SmartVector4
 selected true
 xpos -615
 ypos 51
}
VectorDistort {
 inputs 2
 reference_frame 1
 first 1
 last 100
 reference_frame_set true
 name VectorDistort
 selected true
 xpos -489
 ypos 51
}

3) Connect your viewer to the VectorDistort3 node and then toggle the premult checkbox.

Workaround
Apply a Premult node after the VectorDistort Node.

Reproduced by support
NukeX10.0v1 - LinuxCentos 6.9 - Windows 10 - MacOS 10.12
NukeX10.0v6 - LinuxCentos 6.9 - Windows 10 - MacOS 10.12
NukeX10.5v1 - LinuxCentos 6.9 - Windows 10 - MacOS 10.12
NukeX10.5v5 - LinuxCentos 6.9 - Windows 10 - MacOS 10.12
NukeX11.0v2 - LinuxCentos 6.9 - Windows 10 - MacOS 10.12

Earliest version tested
NukeX10.0v1 (Feature did not exist prior to this release)

Expected behaviour
When the premult filter is selected, the image would produce a radial image with an appropriate alpha generated and masked via the radial and motion vectors.

Actual behaviour
Nothing. The Premult filter is ignored and not applied.