Auto merge of #415 - servo:jdm-patch-3, r=KiChjang

Show backtraces on CI

https://ci.appveyor.com/project/servo/rust-mozjs/build/1.0.619 is pretty frustrating because it shows no useful information.

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Author: bors-servo

.travis.yml

@@ -17,7 +17,7 @@ before_install:
 script:
   - ccache -z
   - CCACHE=$(which ccache) travis_wait cargo build --verbose $FEATURES
-  - CCACHE=$(which ccache) cargo test --verbose $FEATURES
+  - CCACHE=$(which ccache) RUST_BACKTRACE=1 cargo test --verbose $FEATURES
   - ccache -s
 
 notifications:

appveyor.yml

@@ -25,6 +25,7 @@ environment:
     C:\\Program Files\\Git\\cmd;\
     C:\\Program Files\\Git\\usr\\bin;\
     C:\\Program Files\\AppVeyor\\BuildAgent;"
+  RUST_BACKTRACE: "1"
   matrix:
   - TARGET: nightly-x86_64-pc-windows-msvc