As several people noticed, the release tarball of Geiser 0.9 was updated
in place some time ago.

The story is: Federico found that Geiser 0.9 does not contain some files
for Chibi and Chez, so he let the upstream know about it¹, and added
'geiser-next' package².  Then JAOR (the maintainer of Geiser) updated
0.9 tarball in place.

So since Geiser 0.9 contains those missing files for Chibi and Chez now,
I think we can deprecate 'geiser-next' again (along with updating the
hash of the 'geiser' source tarball), WDYT?

¹ https://github.com/jaor/geiser/issues/188
² http://git.savannah.gnu.org/cgit/guix.git/commit/?id=6af886f492a7718a992226d1c2baac7cae04b407