When loading files specified in Task metadata, Puppet specifies which mounts those files can be loaded from. This adds the scripts mount to the list of mounts that Task files can be loaded from.
Merged to 6.x in https://github.com/puppetlabs/puppet/commit/a64d9e31537843bbc20cf824a986c7829d8b9644
passed main CI as part of https://github.com/puppetlabs/puppet/commit/8ed2564a3b0978ce0880af904df56d79637c15e8