It's hard to tell if pasted content gets 'accepted' since you can't actually see it - well, I can't tell the difference between •••••••• and password, so it's hard for me to tell if it's truncated or not.

I didn't look into the code, but if the main site is limited to 50, then I doubt it is going to allow more somewhere else. Try changing it to a password that is only 49 characters and see if it works.