add printout and "strict mode" to bash script

# NOTE: this does not check e.g. for float_ref_branchname actually existing and will silently return ivas-float-update if not

#       Use branch-follows-porting-naming-convention.sh for that

set -euxo pipefail

if [ $# -ne 1 ]; then

  echo "Usage: $0 <branchname>"

  exit 1