The variable should be in quotes for the check to work
Testing the behavior in bash:
current behavior:
$ config_file=""
$ if [ -n ${config_file} ]; then echo a; fi
a
$ config_file="abc"
$ if [ -n ${config_file} ]; then echo a; fi
a
behavior with quotes:
$ config_file=""
$ if [ -n "$config_file" ]; then echo a; fi
$ config_file="abc"
$ if [ -n "$config_file" ]; then echo a; fi
a
Change-Id: Iba956d9d4f43b925848174a632aabe58999be74b
c336b87342