Functor application in PR#6435 fail after commit 15405 #6593
Original bug ID: 6593
Commit 15405 in trunk breaks the basic-modules test in the testsuite.
Comment author: @garrigue
Fixed in trunk at revision 15413.
This is actually a very interesting bug, because the cause is not commit 15405,
This is now fixed in trunk by forcing such a (lazy) substitution.