The issue here was, that I had
or some other kind of space which prevented strip
from doing what it does best.
My solution, first replace all my spaces with spaces:
a.gsub("\u00A0", " ")
(I tried a.gsub(" ", " ")
at first, but no luck)
tada!
Now I got my expected a.strip
result :)
(Maybe there is a clearer way to do this, if so let me know)