The "start_mongo_orchestration" Evergreen script on Windows invokes taskkill.exe to stop all python.exe processes, before actually starting mongo-orchestration. The script's invocation of taskkill.exe currently generates an invalid argument error. One guess as to how this regression was originally introduced is that the Windows version that these tasks run on was changed.

Link to example failure: https://evergreen.mongodb.com/task/cxx_driver_legacy_windows_64_msvc2010_dbg_dyn_dyn_client_test_latest_dca7dd6971573af014606b151834ad82c7d56bb0_16_10_28_21_14_17

Relevant excerpt from task logs:

 [2016/11/03 20:04:54.761] taskkill.exe /fi python /f
 [2016/11/03 20:04:54.774] ERROR: The search filter cannot be recognized.