^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]+ \(include\)$
