Auto merge of #4990 - Eh2406:Zno-index-update, r=alexcrichton
authorbors <bors@rust-lang.org>
Wed, 31 Jan 2018 22:14:53 +0000 (22:14 +0000)
committerbors <bors@rust-lang.org>
Wed, 31 Jan 2018 22:14:53 +0000 (22:14 +0000)
add a -Z no-index-update for crater and benchmarking

This is a fix for #3479


Trivial merge