BF: fix argument parsing
Reported here: https://www.jiscmail.ac.uk/cgi-bin/wa-jisc.exe?A2=FSL;c858e06b.2112 and here: https://www.jiscmail.ac.uk/cgi-bin/wa-jisc.exe?A2=FSL;495523a1.2210
I forgot to apply the fix after the first report.
Occasionally bedpostx_postproc_gpu.sh
will be passed an empty string as an argument, which causes the -z "$2"
test to return false. The test needs to check whether the $2
variable is set, as opposed to testing whether it is non-empty.