^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]+ \(include\)$
