When using the labelledSteps plugin, I have part of my script which takes advantage of bash. In the unlabelled "sh" commands, I could do the following:

sh '''

#!/bin/bash

set -o pipefail

<code dependent on pipefail>

'''

With labelledShell, this type of shebang notation doesn't work:

labelledShell label: 'my bash', script: """

#!/bin/bash

set -o pipefail

<code dependent on pipefail>

"""