In the thread beginning here (https://lists.gnu.org/
archive/html/help-guix/2016-11/msg00000.html), I was given the advice to
install icedtea@2.6 and see if that fixes my keystore problem.

But I have no idea how to do so with a manifest file. I don't want to run
`guix package -i` commands by hand; I want a manifest file.

Running `guix package -m` on a file with this line `(list icedtea-2.6
"jdk")` gives an error "In procedure module-lookup: Unbound variable:
icedtea-2.6".

I get the same error for the following lines:

`(list icedtea-2.6.6 "jdk")`
`(list icedtea@2.6.6 "jdk")`

`guix package -s icedtea` reports that there is a version 2.6.6. How do I
specify this in a manifest file? Thanks.