What about the possibility of changing the package name but *not* the soname. That would allow to catch all the dependencies within Debian, but would neither diverge the soname nor detect dependency breakage with non-packaged builds.
That said, libcurl is popular enough and basic enough I'd expect there are proprietary packages running around that do link against it, and avoiding soname divergence seems like a really good idea for libcurl. I think libcurl may be one of the packages where ABI greater than Debian is more rather than less important. --Sam
