Neovim plugin/addon packaging

[Jack Hill]

Greetings Guix,

I'd like to improve the experience of installing Neovim plugins/add-ons 
with Guix. I've submitted #48112 [0] which adds an XDG_DATA_DIRS search 
path so nvim (the Neovim executable name) will be able to find plugins 
installed by guix at …/share/nvim/site.

Currently, we only have one such package, neovim-syntastic. I'd like to 
add more. Many plugins are compatible with both vim and nvim. However, 
they search for plugins at different paths. Therefore, the vim-syntastic 
and neovim-syntastic packages, which use the copy-build-system, differ 
only in the destination directories of the install-plan (and changing 
"Vim" to "Neovim" in the description).

My initial inclination is to remove the duplication of maintaining two 
install-plans (and other arguments) by creating a procedure that would take 
as input a Vim package that uses copy-build-system and output a Neovim 
package with the install-plan re-written.

Perhaps that solution would be overwrought. How would you recommend 
handling this situation?

[0] https://issues.guix.gnu.org/48112

Best,
Jack