^CMake Error at [^
]*/Modules/ExternalProject.cmake:[0-9]+ \(message\):
  ExternalProject 'proj' step 'update' is marked INDEPENDENT but depends on
  step 'custom' that is not marked INDEPENDENT.
Call Stack \(most recent call first\):
  BadIndependentStep2.cmake:[0-9]+ \(ExternalProject_Add_Step\)
  CMakeLists.txt:[0-9]+ \(include\)$
