This commitid is the current head of my MR branch
  https://github.com/colin-kiegel/rust-derive-builder/pull/253
  https://github.com/ijackson/rust-derive-builder/tree/field-builder
Using the commitid prevents surprises if that branch is updated.

We will require this newer version of derive_builder.  The version
will need to be bumped again later, assuming the upstream MR is merged
and upstream do a release containing the needed changes.

We will need the new version of not only `derive_builder_core` (the
main macro implementation) but also`derive_builder` for a new error
type.