Dependencies of first build are still loaded for all next builds with an easystack file

[bedroge]

I was installing a whole bunch of apps using an easystack file, and suddenly it crashed at the installation of zlib-1.2.12.eb because $EBROOTZLIB was already set. I hadn't done that myself (started with a clean environment), and after inspecting the log file, I noticed that for all installations after the very first one Easybuild was warning that a bunch of modules were loaded. This list consisted of the (build) dependencies of the first application that it installed.

I was able to reproduce it with a simple example, using this easystack file:

easyconfigs:
  - attr-2.5.1-GCCcore-11.2.0.eb
  - zlib-1.2.12.eb

Installing this with eb -f --experimental --easystack test.yml (note that the dependencies of attr are already available on my system) results in a successful installation of attr, but:

== FAILED: Installation ended unsuccessfully (build directory: 
/data/eb/build/zlib/1.2.12/system-system): build failed (first 300 chars): 
Module is already loaded (EBROOTZLIB is set), installation cannot continue. 
(took 0 secs)

The attr log has:

== 2023-01-25 12:45:58,939 easyblock.py:2248 WARNING Loaded modules detected: ['EasyBuild/4.7.0']

But the one for zlib has:

== 2023-01-25 12:46:04,854 easyblock.py:2248 WARNING Loaded modules detected: ['EasyBuild/4.7.0', 'GCCcore/11.2.0', 'zlib/1.2.11-GCCcore-11.2.0', 'binutils/2.37-GCCcore-11.2.0']

So it looks like it didn't unload the attr (build) dependencies. This is with EB 4.7.0, and based on some older logs of applications built with a similar easystack (but with the old structure) and EB 4.6.2, the latter version didn't have this issue.

[boegel]

That likely introduced with the changes in #4057, which includes a large refactor.
We're probably not properly resetting the build environment after completing an installation?

Thanks a lot for reporting this @bedroge, we'll look into catching this in a CI test, and fixing it - as it is now, easystack files aren't exactly production ready, that's clear...