build: remove needless BASE_TESTS env

Author: tesuji

.travis.yml

@@ -47,11 +47,9 @@ matrix:
   include:
     # Builds that are executed for every PR
     - os: osx # run base tests on both platforms
-      env: BASE_TESTS=true
     - os: linux
-      env: BASE_TESTS=true
     - os: windows
-      env: CARGO_INCREMENTAL=0 BASE_TESTS=true OS_WINDOWS=true
+      env: CARGO_INCREMENTAL=0 OS_WINDOWS=true
 
     # Builds that are only executed when a PR is r+ed or a try build is started
     # We don't want to run these always because they go towards
@@ -89,7 +87,7 @@ matrix:
       if: repo =~ /^rust-lang\/rust-clippy$/ AND branch IN (auto, try)
   allow_failures:
     - os: windows
-      env: CARGO_INCREMENTAL=0 BASE_TESTS=true OS_WINDOWS=true
+      env: CARGO_INCREMENTAL=0 OS_WINDOWS=true
 
 before_script:
   - |