To reproduce the bug

1. Build the executable:

   stack build bug-repro:exe:bug-repro-exe
   

2. Then repeat to ensure all targets are up-to-date.
3. Insert a newline into src2/Lib2.hs and save
4. Re-run the above command to build the executable. Observe that files are rebuilt despite that the lib2 sublibrary is not a dependency of bug-repro-exe.

Equivalent cabal test

1. Build the executable:

   cabal build bug-repro:exe:bug-repro-exe
   

2. Then repeat to ensure all targets are up-to-date.
3. Insert a newline into src2/Lib2.hs and save
4. Re-run the above command to build the executable. Observe nothing is rebuilt; only "Up to date" is printed.