If the .pyc file can't be written, compileall2 fails silently

[encukou]

During testing upstream, it was found that py_compile, and thus compileall, silently skips writing .pyc files it can't write (because of path size limits; probably also because of permissions etc.).

For Fedora, it would make sense to fail with an exception (or error exit code). It should probably be an option – not everyone will want it.