How to deal with circular BuildRequires ?

[Jonathan Underwood]

Hi,

Tom Tromey and I are working on packaging bbdb for Emacs (see BZ
226800). However, there is a circular BuildRequires. In order that the
Emacs mailreader VM (packaged as emacs-vm) and bbdb integrate
properly, we need to have a BuildRequires: emacs-vm-el in the
emacs-bbdb package, and we need to have a BuildRequires: emacs-bbdb-el
in the emacs-vm package. In other words, both packages require the
elisp source of the other to be present at build time.

Is there an established way of solving this chicken and egg situation?

Thanks,
Jonathan