Auto merge of #3508 - petrochenkov:bsover, r=alexcrichton
authorbors <bors@rust-lang.org>
Fri, 6 Jan 2017 18:46:47 +0000 (18:46 +0000)
committerbors <bors@rust-lang.org>
Fri, 6 Jan 2017 18:46:47 +0000 (18:46 +0000)
Do not treat `warning` and `rerun-if-changed` as user-defined metadata in build script overrides

Fixes https://github.com/rust-lang/cargo/pull/3438#discussion_r94018355
r? @alexcrichton


Trivial merge