HSQL build reports exposed module as hidden, and fails

Hello. I'm trying to install hsql-1.7, and it needs some library "old-time", which appears to be hidden. However, when exposing this library. the compiler and the HSQL build script disagree on whether old-time is exposed.

Configure works:

  /tmp/hsql-1.7 $ runghc Setup.lhs configure
  Configuring hsql-1.7...
  Warning: No license-file field.

Exposing old-time succeeds:

  /tmp/hsql-1.7 $ sudo bash
  /tmp/hsql-1.7 % ghc-pkg expose old-time
  Saving old package config file... done.
  Writing new package config file... done.

  /tmp/hsql-1.7 % ghc-pkg describe old-time | egrep exposed
  exposed: True
  exposed-modules: System.Time

But the build process somehow gets the idea that old-time is hidden:

  /tmp/hsql-1.7 % runghc Setup.lhs build
  Preprocessing library hsql-1.7...
  Building hsql-1.7...

  Database/HSQL.hsc:66:7:
      Could not find module `System.Time':
        it is a member of package old-time-1.0.0.0, which is hidden