^CMake Error at .*/Modules/ExternalProject.cmake:[0-9]+ \(message\):
  Target "SomeInterface" was not generated by ExternalProject_Add.
Call Stack \(most recent call first\):
  Add_StepDependencies_iface.cmake:[0-9]+ \(ExternalProject_Add_StepDependencies\)
  CMakeLists.txt:[0-9]+ \(include\)$