Failed to load interface for ‘Data.Hashable.Generic’ when `cabal install` with module signature

Here is an example package: https://github.com/myuon/failed-to-load-interface

When installing a library that has a signature file (.hsig) and has a module that contains a line `import Data.Hashable.Generic` with ghc-8.2.1 and cabal-2.0, the install failed with an error:

```
Failed to load interface for ‘Data.Hashable.Generic’
no unit id matching ‘hashable-1.2.6.1-14fEJP30YhAG9w115PODz0’ was found
```

This is occurred when executing `cabal install`, but `cabal install --only-dependencies` nor `cabal new-build` does not give any errors.

Also, commenting out the line `import Data.Hashable.Generic` in the module file or `signatures: Foo` in the cabal file will suppress this error.