curl multi_select bug in php 5.3.18+

curl_multi_select() may return -1 forever until you call curl_multi_exec()
See https://bugs.php.net/bug.php?id=63411
https://bugs.php.net/bug.php?id=61141

https://github.com/aslamsayyed/ParallelCurl/commit/c450a37072bd456f9b4790b9c1502715cc196812