Before this commit meaning of limit_posts:
nil: no limit. generate all posts
0: raise error
n ( > 0): generate n posts only
n ( < 0): raise error
else: raise error
After this commit:
nil: same as 0
0: no limit. generate all posts
n ( > 0): generate n posts only
n ( < 0): raise error
else: almost same as 0 (depend on `to_i` result)