Default content location is inferred in an unreliable way.

[matejak]

The content location detection code may not work according to expectations on some platforms, and #79 makes workarounds quite tedious.
As the content location is known at build-time of the package, the content location should be configurable in a straightforward way.

[yuumasato]

How about a better mapping from product+version to datastream?
Along with a fallback to allow selection from locally available datastreams?

[matejak]

This has been kind-of addressed by #146 when DEFAULT_SSG_CONTENT_NAME is there, waiting to be monkey-patched by packagers.
Moreover, that release also restores functionality of the file:// prefix, which can be used to supply a local content file to the installation.