What I mean is if you define
{\mu,\nu}::Indices;
\partial{#}::PartialDerivative;
\phi::Depends(\partial{#});
ex:=\partial_{\mu}{e**(\phi)};
and you apply the product_rule to it, an unexpected result appears:
\phi e**(\phi -1) \partial_{\mu}{e}.
Im not sure if this is a bug or I am implementing in a wrong way the exponential function.