rules: Fix merge script
The previous update !728 (merged) removed the initialization of a dictionary in the
merge
function, leading to duplicates, namely the files not starting
with a rule header.
While we introduced defaultdict
previously to avoid initializing lists
manually, we still need to initialize the dict
in order to keep it in
sync with section_names
.
Sadly the CI did not catch it, nor I. Sorry
Edited by Wismill