Not possible to define template variable with other variables

With the new template engine a few tests were added. One of those tests actually checks if it's possible to include a file that was defined by a variable; this obviously works.

Unfortunately, this doesn't work if one tries to define the variable with another variable or a loop variable.

This used to work until now so this is actually a regression.

The attached test_loop_define.diff extends the current develop tests and should explain what is not working a little bit better. The file test_loop_define_olympus.diff will add the checks to develop-olympus and will show that the tests actually pass on develop-olympus.