Currently only zc.recipe.egg:custom supports setting environment variables, and zc.recipe.egg:develop does not.
My motivation for allowing setting environment in :develop is wendelin.core
https://lab.nexedi.cn/nexedi/slapos/blob/b5faab3b/component/wendelin.core/buildout.cfg
There we have [wendelin.core] part which installs released egg from pypi, and [wendelin.core-dev] part which installs wendelin.core from its latest git version via zc.recipe.egg:develop .
The problem is, wendelin.core for setup.py to work, needs git available, and with slapos we usually don't have git available on base system, so we build it by our own and do something like
[wendelin.core-dev]
recipe = zc.recipe.egg:develop
environment = wendelin.core-dev-env
[wendelin.core-dev-env]
# wendelin.core-dev needs git to build
PATH = ${git:location}/bin:%(PATH)sand the problem is environment does not currently work for zc.recipe.egg:develop, and thus git is not found -> build fails.
In order to support environment in :develop, we just move environment setting/restoring bits from Custom to Base, and provide Base.install() which uses this bits. Custom & Develop .install() becomes ._install() which gets hooked into Base.install() .
I've tested the patch only manually, because currently automated tests are broken in a lot of places for slapos.buildout and zc.recipe.egg .