Building and installing packages with modifications

[白い熊]

Hi Guix: 

This is a question derived from my current trouble with running Guix on 
Android, as seen in: 
http://lists.gnu.org/archive/html/help-guix/2019-02/msg00151.html

Basically: 
— I have Guix running on an armhf Android phone 
— “guix pull” won't complete as it needs to build curl locally, since a 
substitute is unavailable 
— curl local build fails on checking internet connection in one of its tests, 
as is common, as I found out on the web 
— Thus “guix pull” never finishes, and I can't install any packages etc, since 
even without pulling a new version, they also fall into building curl 

I'd like to overcome this, am not sufficiently advanced in Guix, so would like 
to receive ideas / tips on how to best / easiest do this. 

Currently, I'm thinking of two options. 

① Build curl locally, without the failing tests. 
② Install an older substitute version of curl already built. 

Ad ①: 
— I've found there is an environment variable (INTERNET_TEST or something) you 
can set so the test is not run during auto build run. It's ignored if “guix 
build curl” is run with it. 
— Can environment variables be passed to “guix build” so they are then honored 
during build? 
— If not, can I instruct “guix build” to not run “make test”? 
— If both not, can I then carry out the individual stages of a package build in 
Guix, so I can skip the test phase? 
— If I build it in any of these ways, will “guix package -i curl” then install 
this version in the profile? 
— If not, can I install it any other way then, so I can commence with “guix 
pull” without it being rebuilt? 

Ad ②: 
— Is there any way I can search the substitute servers for the latest built 
substitute of a package? 
— How can I then install it? 

If none of these, is there another way to overcome my problem? 

Many thanks for any advice! :@) 
--
白い熊