The package has a debian/watch file, but the last attempt
to use it for checking for newer upstream versions failed with
an error:
In debian/watch no matching files for watch line http://sphinxsearch.com/downloads/release/ \.\./accept\.php\?file=sphinx-(.*)-release\.tar\.gz debian uupdate
testing migration
This package will soon be part of the auto-re2 transition. You might want to ensure that your package is ready for it.
You can probably find supplementary information in the
debian-release
archives or in the corresponding
release.debian.org
bug.