~/tmp $ stack new repro
...
~/tmp $ cd repro/
~/t/repro $ stack config set resolver nightly
Selected resolver: nightly-2016-10-13
/home/simon/.stack/global-project/stack.yaml has been updated.

This bug probably crept in during 0bdab6e.

I think I missed that the Config that I get from withMiniConfigAndLock doesn't contain any information on the current project, so getStackYaml always ends up looking for the global project.

I probably won't get around to fixing this until Sunday…

I also think that it would be good to have safeguards against bugs like this, for example by assigning different types to Configs from MiniConfigs and BuildConfigs or something similar.