Fixed bug in install-from-repository (issue #3472)
Install from repository (e.g., of /dotlrn) was horribly broken, see, e.g., issue #3472. Furthermore, this bug was hard to debug, since it showed up just during a complex installation attempts involving install.xml, and it requires fetching from the repository. Therefore, the debug rounds were quite time-consuming.
There were several problems involved:
1) dotlrn/install.xml was trying to set the theme to the dotlrn-bootstrap3-theme, which was not loaded from the repository
2) The loading order was not correct, since the theme requires an existing dotlrn instance to register the theme templates there.
3) The tests in install::xml::action::mount checking, if the package was already mounted were incorrect, probably since many years. It looks to me as some refactorings of the "get_node_id" semantics (many years ago) were not reflected in this code. This bug let the code assume, that the package was already mounted. Therefore, the package was never mounted, causing a long tail of subsequent issues.
4) the site_node::instantiate_and_mount call in install::xml::action::mount was called with incorrect parameters, causing overwriting of the site root node, leaving the site completely unusable.