TillmannRendel authored Sep 08, 2013 and Duncan Coutts committed Oct 25, 2013

The goal is to learn the installed package id of the package we just
installed, as necessary for #1860. We achieve this by inserting an
additional call to "setup register" that produces the installed package
information in a file. We read and parse that file and could now return
the installed package id, but it is not clear what interface would be
appropriate.