In the commit d8bf2810ff we hoisted
the userOptionFields array to a module-level variable, but kept
the code inside save() the same. This causes an issue where if
save() is called twice on the same user with some array of user
option fields, the userOptionFields array is mutated, which means
the second save is likely not saving the fields intended.
This commit fixes the issue by not mutating the array. We cannot
change them into consts though, because we have an API to add more
items to the array.
Martin Brennan
357186ab7e