LoginToboggan interferes with other modules altering registration form.

rev 1.83.2.22 has an important fix in it so that other modules' submit handlers that are added to the user_register form are not totally clobbered. Woohoo!

However, there remains one detail, which is kind of obtuse. I'll do my best to explain succinctly:

- Normally, without LoginToboggan, what happens with the registration form is user_register_submit() is called, then any functions that have been added to the form's #submit property. Thus under normal circumstances, any modules adding stuff to #submit on user_register can safely assume that the registration routines have happened and the user already exists in the database.
- However, the way LoginToboggan works is it unsets the user_register_submit() call altogether, in favour of its own. This by itself wouldn't be a problem, except that LoginToboggan starts with "L" and is weighted "0". Which means that any other contributed modules that start with A-L and try to add #submit handlers to this form, expecting the user to already exist when they do so, are in for a nasty surprise.

I ran into this issue with Bio module during development of the Allow CCK fields on the registration form feature.

There are two ways to fix this problem:
a) All contributed modules that start with the letter A-L and altering user_register's #submit property set their weight upon installation to 1 or something higher than LoginToboggan's default 0, on the off-chance their module is used on the same site as LoginToboggan.
b) LoginToboggan sets its weight on install to -1, so that it emulates user_register_submit(), and always comes before any other "normal" #submit handlers on the form.

My vote is for b), since LoginToboggan is the one doing something weird here. hunmonk disagreed on IRC, and asked me to make an issue for it when I could, so here it is. :)