Mac OS X 10.8.5
Processor 2.8 GHz Intel Core i7
Memory 8 GB 1067 MHz DDR3
Graphics ATI Radeon HD 4850 512 MB
Broken: 2.70a f93bc76
**Short description of error**
Render artifacts appear when using the Transform composite node. Specifically when X offset is a positive value.
**Exact steps for others to reproduce the error**
1. Add an object and a lamp to your scene.
2. In the Node Editor (Composite) do Add > Distort > Transform and set X to a positive value.
3. Adjust the camera so that the camera's view just encompasses your object to be rendered.
It seems that when the rendered object is not near the edge of the camera's view the problem does not appear.
4. Set your render resolution to something other than the default (Not 1920x1080 or 1920x1920 either).
Note that at certain resolutions the problem does not appear. For example 1920x1920 appears normal but 360x360, 800x800, etc reveals the bug.
A screenshot that quickly shows the problem:
A .blend that demonstrates the problem in a very simple node setup.
A .blend that demonstrates a real case where this bug interfered with a render.
I developed a node tree to create a drop shadow and noticed a shadow on the edge of the render that shouldn't have been there.