Variable: before-hack-local-variables-hook

Normal hook run before setting file-local variables.
It is called after checking for unsafe/risky variables and
setting `file-local-variables-alist', and before applying the
variables stored in `file-local-variables-alist'. A hook
function is allowed to change the contents of this alist.

This hook is called only if there is at least one file-local variable to set.