Move to subprocess disabled condor_root_switchboard errors
condor_root_switchboard always closes stderr. (From the condor_root_switchboard README):
Note that the file descriptor used by the switchboard for error output (i.e. the second file descriptor specified on the command line) is always closed when the job starts, even if it is added to this list. This behavior may change in future versions. If you want error output from the switchboard to be combined with stderr output from the job, dup the stderr file descriptor to a new descriptor and specify this new descriptor as the error descriptor for the switchboard.
We were using the shell to duplicate the fd, now we should do it in code.