Esteemed maintainers,

It seems that (wrap-program ...) over-writes the previous wrapping of a
package done by the build system.

This does not happen for many (wrap-programs) called in the modify-phases
section of the package definition itself.

Attached is a package definition for ruby-ronn-ng, that demonstrates this
issue. The custom (wrap-program)-s
called from the package definition seem to over-write the definitions of
GEM_ENV as made by the 'wrap %standard-phase
of the ruby-build system.
The wrappings made by 'wrap %standard-phase can be seen during the custom
'DEBUG phase. The subsequent 'wrap-program1
and 'wrap-program2 add more environment variables to the wrapping, but on
checking the contents of `which ronn`, once
it is installed (using `less $(which ronn)`), it can be verified that the
GEM_ENV package definitions have been overwritten.

This may just be a ruby-build-system issue. Or perhaps it might be
something that permeates over a few more build systems.
That still remains to be tested.

Attached are a few different versions of the package definitions for
ruby-ronn-ng for the ease of those who would like to
verify this.
1. ruby-ronn-ng-standalone.scm : To be tested using `guix time-machine --
build --verbosity=2 --file=ruby-ronn-ng-standalone.scm`[1]
2. ruby-ronn-ng.scm : To be appended to the end of the
gnu/packages/ruby.scm file in local guix checkout, and be tested using the
local version
3. ruby-ronn-ng.patch : To be applied to local guix checkout

[1] - This package definition needs ruby-mustache, which has only recently
been added to guix. Hence, the time-machine.

NOTE: `ronn` does not work even with `propagated-inputs`. See this patch as
to why:
https://aur.archlinux.org/cgit/aur.git/tree/0001-allow-mustache-1.0.patch?h=ruby-ronn-ng