[BUG] unable to use a hostfile with a name that is not "hostfile"

Describe the bug
I am trying to launch multiple Megatron-DeepSpeed jobs on a slurm based cluster. For each job, I want to create a different hostfile called hostfile_${SLURM_JOBID}. However, when I tried to do this along with deepspeed --hostfile=hostfile_${SLURM_JOBID}, I saw from the logs that deepspeed was unable to detect the hostfile and set the worldsize to 4 (which is the number of GPUs on a single node) erroneously. Interestingly, creating a hostfile with the name 'hostfile' does not lead to this error.

Screenshots
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System info (please complete the following information):

• Perlmutter supercomputer

Launcher context

• launching with the deepspeed launcher

Docker context
n/A

Additional context
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