  Recently, Jaekel and Reynaud put forth a metric linear extension of general
relativity which, in the intentions of its proponents, would be able, among
other things, to provide a gravitational mechanism for explaining the Pioneer
anomaly without contradicting either the equivalence principle or what we know
about the planetary motions. In this paper we perform an independent test of
such an hypothesis by showing that the planets' orbits are, in fact, affected
by the suggested mechanism as well and comparing the resulting effects with the
latest observational determinations. It turns out that the predicted perihelion
precessions, expressed in terms of an adjustable free parameter zeta_P set
equal to the value used to reproduce the magnitude of the Pioneer anomalous
acceleration, are quite different from the observationally determined
extra-advances of such Keplerian element for the inner planets. Conversely, the
values obtained for zeta_P from the determined perihelion extra-rates of the
inner planets turn out to be in disagreement with the value which would be
required to accommodate the Pioneer anomaly. As a consequence, the suggested
explanation of gravitational origin for the Pioneer anomaly, based on the
assumption that zeta_P is constant throughout the Solar System, should be
rejected, at least in its present form.

General Relativity and Quantum Cosmology;Astrophysics;High Energy Physics - Phenomenology;Space Physics