Switch travis to rustup and one build per PR

Like AppVeyor this only schedules one build to run on PRs, and everything else
will exit quickly. This'll help keep the queue clear for PRs when they come
through. Also switch Travis to using rustup instead of `rustup.sh` manually.

Author: alexcrichton

.travis.yml

@@ -2,6 +2,7 @@ sudo: required
 dist: trusty
 services:
   - docker
+language: rust
 
 matrix:
   include:
@@ -13,6 +14,7 @@ matrix:
     - os: linux
       env: TARGET=x86_64-unknown-linux-gnu
            DOCKER=alexcrichton/rust-slave-dist:2015-10-20b
+           NO_ADD=1
 
     # Cross builds happen in the `rust-slave-linux-cross` image to ensure that
     # we use the right cross compilers for these targets. That image should
@@ -104,6 +106,7 @@ matrix:
     - os: osx
       env: TARGET=x86_64-apple-darwin
            MACOSX_DEPLOYMENT_TARGET=10.7
+           NO_ADD=1
 
 cache:
   # We're going to download things we don't necessarily want to cache into the `target` directory, so
@@ -118,33 +121,23 @@ branches:
     - stable
     - auto
 
-notifications:
-  webhooks: http://buildbot.rust-lang.org/homu/travis
-
 install:
-  - sudo pip install awscli
-  - aws configure set preview.cloudfront true
-  - curl https://static.rust-lang.org/rustup.sh |
-    sh -s -- --prefix=$HOME/rust --spec=nightly-2017-04-25 --with-target=$TARGET
+  - if [ -z "$NO_ADD" ]; then rustup target add $TARGET; fi
 
 script:
-  - mkdir -p target/$TARGET
-  - if [ ! -z "$DOCKER" ]; then
-      sh ci/build-run-docker.sh "$DOCKER" "$TARGET" "$SKIP_TESTS";
+  - mkdir -p target/$TARGET;
+  - >
+    if [[ "$TRAVIS_PULL_REQUEST" == "false" || "$ALLOW_PR" == "1" ]]; then
+        if [ ! -z "$DOCKER" ]; then
+            sh ci/build-run-docker.sh "$DOCKER" "$TARGET" "$SKIP_TESTS";
+        else
+            PATH=$HOME/rust/bin:$PATH sh ci/run.sh;
+        fi
     else
-      PATH=$HOME/rust/bin:$PATH sh ci/run.sh;
+        echo 'skipping build';
     fi
-  # Install kcov dependencies
-  # FIXME: busted!
-  #- if [ "$TARGET" == "x86_64-unknown-linux-gnu" ]; then
-  #    wget https://github.com/SimonKagstrom/kcov/archive/master.tar.gz;
-  #    tar xzf master.tar.gz && mkdir kcov-master/build && cd kcov-master/build && cmake .. && make;
-  #    sudo make install && cd ../..;
-  #    echo "Uploading coverage... $TRAVIS_JOB_ID";
-  #    find target/debug/deps/*-* -executable -exec kcov --verify --coveralls-id=$TRAVIS_JOB_ID --exclude-pattern=/.cargo target/kcov '{}' \;;
-  #    find target/debug/*-* -executable ! -name rustup-rs -exec kcov --verify --coveralls-id=$TRAVIS_JOB_ID --exclude-pattern=/.cargo target/kcov '{}' \;;
-  #  fi
-  # prepare for a deploy if this will be a deployment
+
+before_deploy:
   - bash ci/prepare-deploy-travis.sh
 
 deploy:
@@ -163,4 +156,6 @@ deploy:
 
 # FIXME: I don't know if this really works
 after_deploy:
+  - sudo pip install awscli
+  - aws configure set preview.cloudfront true
   - aws cloudfront create-invalidation --paths "rustup/$TARGET/* rustup/dev/$TARGET/* rustup/www/* rustup/dev/www/* rustup/* rustup/dev/*"