CMake Error at .*/Modules/ExternalData.cmake:[0-9]+ \(message\):
  Bad %\(algo:0BadMap\(\) in URL template:

   file:///path/to/%\(algo:0BadMap\(\)/%\(hash\)

  The transform name must be a valid C identifier.
Call Stack \(most recent call first\):
  BadAlgoMap2.cmake:[0-9]+ \(ExternalData_Add_Target\)
  CMakeLists.txt:3 \(include\)