BRepMesh_IncrementalMesh fails to mesh a conical surface

Running the code attached (Attachment 2 (CPP)) against version 7.8.0 results in a failure to mesh the conical surface of the step attached (Attachment 1 (STEP)). The linear and angular deflections used are 0.01 and 0.5 respectively. The same code succeeds with version 7.6.1, so it looks like a regression. Note that setting ForceFaceDeflection to true does not change the result. In order to mesh the conical surface correctly with 7.8.0, the linear and angular deflection parameters have to be increased to 0.22 and 0.71, which seem high (especially the linear deflection).