ID 386221 - VectorBlur effects the internal alpha of objects, even when uv alpha is enabled

Problem summary
VectorBlur effects the internal alpha of objects, even when uv alpha is enabled

This affects uv passes from ScanlineRender and V-Ray, it may affect other types of maps as well

Customer reported version
nuke.10.5v1

Customer reported platform
windows7

Steps to reproduce

1) Open the attached Nuke script

2) View the VectorBlur node's Alpha channel, and decrease the gamma, an internal artifact appears. When applying blur directly in the ScanlineRender node, this does not happen:

Expected behaviour

For the internal alpha not to be affected when uv alpha is set to the total alpha

Actual behaviour
Dark edges appear inside the main alpha

Reproduced by support

This bug has been reproduced in:

Nuke 11.3v2 - Windows 10 - CentOS 6.9 - MacOSX 10.13

Nuke 11.2v1 - Windows 10

Nuke 11.1v1 - Windows 10

Nuke 11.0v1 - Windows 10

Nuke 10.5v1 - Windows 10

Nuke 10.0v1 - Windows 10 - CentOS 6.9 - MacOSX 10.13

Earliest version tested
Nuke 10.0v1 - This feature did not exist before this version