Tweakig -lowmem to be more eager

[Anonymouse]

I have CircleCI set up to test my project when I push to GitHub.

For a free user there the memory restriction is pretty severe (4 
Gb), and as such non-trivial programs cannot be compiled without 
separate compilation.

This sounded like a clear-cut case for -lowmem, but the process 
is still killed from allocating too much.

circleci at ab1d64fc40cf:~/project$ dub test
Running custom 'unittest' configuration.
Performing "unittest" build using /usr/bin/dmd for x86_64.
cachetools 0.1.2: building configuration "library"...
requests 1.0.8: building configuration "std"...
kameloso 1.1.3+commit.31.g11ba25fd: building configuration 
"unittest"...
Killed
/usr/bin/dmd failed with exit code 137.

dub test -v shows -lowmem being properly passed to dmd.

What makes it decide to collect? What triggers it?