This file is contained in the './lib' directory.

The directory name './lib' conflicts with the './lib.rs' file name.

'lib.rs' defines 3 external modules:

    * mod a;
    * mod b;
    * mod c;

Module resolution will fail if we look for './lib/a.rs' or './lib/a/mod.rs',
so we should fall back to looking for './a.rs', which correctly finds the module that
rustfmt should format.

'./lib/b.rs' and './lib/c/mod.rs' exist at the default submodule paths so we should be able
to resolve these modules with no problems.