[R-pkg-team] Bug#964371: dh-r: generate wrong dependencies for source package with multiple binary packages

[Dylan Aïssi]

Package: dh-r

We have more and more source packages generating more than a unique R
binary package (i.e. they also generate python, library, ...) like
isospec, rosa and r-bioc-mofa.

Currently, dh-r assigns substvars to the first binary package from
d/control. If this package is not the R package but a python or
whatever, then dependencies of the generated R binary package will be
wrong (empty).

dh-r should assign substvars to the first **R** binary package in d/control.

See: https://lists.debian.org/debian-med/2020/07/msg00045.html