title: stringr: U_REGEX_BAD_INTERVAL error
body: <p>I have a regular expression that is correctly parsed by <code>grepl</code> but generates an error when used as <code>pattern</code> of <code>str_extract_all</code>.</p>
  
  <p>I'm using <code>stringr</code> v1.0.0, <code>R</code> v3.2.3 under OSX.</p>
  
  <p>In <a href="https://stackoverflow.com/questions/30061371/r-regex-engine-changed-in-3-2-0">this</a> question a regex passed to a <code>stringr</code> generates a similar error, yet the solution proposed doesn't apply in my case. </p>
  
  <pre><code>require(stringr)
  
  string &lt;- "Decreto Legislativo 6 marzo 1992, n. 248; G.U. n. 77 del 1° aprile 1992"
  
  it_months &lt;- c("gennaio","febbraio","marzo","aprile","maggio","giugno","luglio",
                 "agosto","settembre","ottobre","novembre","dicembre")
  grep_it_date &lt;- paste0("\\d{1-2}(º?) (", paste(it_months, collapse="|") ,") \\d{4}$")
  
  grepl(grep_it_date, string)
  # [1] TRUE
  
  dates_from_string &lt;- str_extract_all(tolower(string), grep_it_date, simplify = TRUE)
  # Error in stri_extract_all_regex(string, pattern, simplify = simplify,  : 
  #                                   Error in {min,max} interval. (U_REGEX_BAD_INTERVAL)
  </code></pre>