Win 8 - GeForce 980Ti
Worked: 2.76 (any)
Short description of error
First: this is happening only with Amaranth toolset addon, so i'm not sure if the bug is on that side.
The samples values for Diffuse, Glossy, Transmission, etc... of the Branched Path Tracing mode can be set to 0, giving unespected render results
Exact steps for others to reproduce the error
Enable Amaranth toolset addon - set Diffuse, Glossy, Transmission, etc to lower than 4 - click on Set New Render Samples - click on 25%