encoding issue about rvest

[hadley]

I don't know why the last example works, but specifying the encoding is unrelated:

html(readLines(url)) %>% html_nodes('title') %>% html_text()
[1] "オファー (12月5日＜金＞)"
There were 12 warnings (use warnings() to see them)
> warnings()
Warning messages:
1: In grepl("^http", x) : input string 5 is invalid in this locale
2: In grepl("^http", x) : input string 7 is invalid in this locale
3: In grepl("^http", x) : input string 10 is invalid in this locale
4: In grepl("^http", x) : input string 11 is invalid in this locale
5: In grepl("^http", x) : input string 12 is invalid in this locale
6: In if (grepl("^http", x)) { ... :
  the condition has length > 1 and only the first element will be used
7: In grepl("<|>", x) : input string 5 is invalid in this locale
8: In grepl("<|>", x) : input string 7 is invalid in this locale
9: In grepl("<|>", x) : input string 10 is invalid in this locale
10: In grepl("<|>", x) : input string 11 is invalid in this locale
11: In grepl("<|>", x) : input string 12 is invalid in this locale
12: In if (grepl("<|>", x)) { ... :
  the condition has length > 1 and only the first element will be used