Auto merge of #2962 - alexcrichton:demote-error, r=brson
authorbors <bors@rust-lang.org>
Fri, 5 Aug 2016 16:13:51 +0000 (09:13 -0700)
committerGitHub <noreply@github.com>
Fri, 5 Aug 2016 16:13:51 +0000 (09:13 -0700)
Demote duplicate build target error to a warning

Added in #2847 this ended up unfortunately breaking the `regex` crate on
nightly, so let's just issue a warning for awhile first. Eventually we can
promote this to an error if it becomes a problem.


Trivial merge