Try radically changing the Travis script

.travis.yml

@@ -1,35 +1,26 @@
-matrix:
-  include:
-    - language: rust
-      rust:
-      - stable
-      - beta
-      - nightly
-      matrix:
-        allow_failures:
-          - rust: nightly
-      cache: cargo
+language: python
 
-    # http://kiki.to/blog/2016/02/04/talk-continuous-integration-with-lua/
-    - language: python
-      env:
-        - LUA="lua=5.1"
+env:
+  - RUST="stable" LUA="lua=5.1"
+  - RUST="beta" LUA="lua=5.1"
 
-      before_install:
-        - pip install hererocks
-        - hererocks lua_install -r^ --$LUA
-        - export PATH=$PATH:$PWD/lua_install/bin
+before_install:
+  - pip install hererocks
+  - hererocks lua_install -r^ --$LUA
+  - export PATH=$PATH:$PWD/lua_install/bin
+  - curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain $RUST
 
-      install:
-        - luarocks install luafilesystem
-        - luarocks install busted
-        - luarocks install luacov
-        - luarocks install luacov-coveralls
-        - luarocks install luacheck
+install:
+  - luarocks install luafilesystem
+  - luarocks install busted
+  - luarocks install luacov
+  - luarocks install luacov-coveralls
+  - luarocks install luacheck
 
-      script:
-        - cd plugin && luacheck . && cd ..
-        - lua -lluacov spec.lua
+script:
+  - cd plugin && luacheck . && cd ..
+  - lua -lluacov spec.lua
+  - cargo test --verbose
 
-      after_success:
-        - luacov-coveralls -e $TRAVIS_BUILD_DIR/lua_install
+after_success:
+  - luacov-coveralls -e $TRAVIS_BUILD_DIR/lua_install