[fix] manage - fix miss usage of 'set -e'

The philosophy of set -e is typically that it only exits upon uncaught
errors. Here, the presence of || outside the subshell seems to tell the shell
that the error inside the subshell is 'caught' and therefore set -e does not
cause an exit after false [1].

The shell does not exit if the command that fails is ... part of any command
executed in a && or || list except the command following the final && or ||, any
command in a pipeline but the last, or if the command’s return status is being
inverted with ! [2]

[1] https://unix.stackexchange.com/questions/296526/set-e-in-a-subshell
[2] https://www.gnu.org/software/bash/manual/html_node/The-Set-Builtin.html#The-Set-Builtin



BTW: fix error reported by 'make test.shell'

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>