Regression in test suite of probor-0.2.1 in Rust 1.15

[brson]

https://github.com/tailhook/probor at d0be60ec37ded2eee0f851887e2d7c06fe2e7021

101 brian@ip-10-145-43-250:~/dev/probor/rust⟫ rustc +beta -Vv
rustc 1.15.0-beta.1 (d9a0f0df7 2016-12-19)
binary: rustc
commit-hash: d9a0f0df7051c603011d6b60fbdd155318fc47f3
commit-date: 2016-12-19
host: x86_64-unknown-linux-gnu
release: 1.15.0-beta.1
LLVM version: 3.9

brian@ip-10-145-43-250:~/dev/probor/rust⟫ cargo +beta test
   Compiling byteorder v1.0.0
   Compiling libc v0.2.18
   Compiling byteorder v0.5.3
   Compiling cbor-codec v0.5.0
   Compiling probor v0.2.1 (file:///mnt2/dev/probor/rust)
error[E0428]: a macro named `_probor_pattern` has already been defined in this module

error: aborting due to previous error

Build failed, waiting for other jobs to finish...
error: Could not compile `probor`.

cc @jseyfried I haven't seen one quite like this.

cc @tailhook

[jseyfried]

Fixed in #38793.