Fix jsub's dependence on $HOME's existence.

$HOME isn't set for CGIs so jsub's output files defaulted to the root
directory and thus caused the jobs to fail.  This fixes only bug
#48726; for submitting jobs from CGIs bug #48722 needs to be addressed
as well.

Bug: 48726
Change-Id: I7d03609b0c901527c0dcd492ba99af64e517a13e
Merge "Fix jsub's dependence on $HOME's existence."