I had programs.bash.sessionVariables.CDPATH = ... defined in the
different nix files. One was taken into account and the other one
ignored.
Turns out plain "types.attrs" has the following merging strategy:
===
merge = loc: foldl' (res: def: res // def.value) { };
===
Changing it to "attrsOf", the module system warned me of the conflicting
values.
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