The package contains a preinst maintainer script that uses an unusual and non-essential interpreter but does not declare a pre-dependency on the package that provides this interpreter.
preinst scripts should be written using only essential interpreters to avoid additional dependency complexity. Please do not add a pre-dependency without following the policy for doing so (Policy section 3.5).
Refer to Debian Policy Manual section 7.2 (Binary Dependencies -
Pre-Depends) for details.