Don't overwrite RUBYOPT

c.f. sue445/omniauth-chatwork#13

.travis.yml

@@ -16,7 +16,7 @@ before_script:
   - chmod +x ./cc-test-reporter
   - ./cc-test-reporter before-build
 script:
-  - bundle exec rspec
+  - RUBYOPT=$RSPEC_RUBYOPT bundle exec rspec
 after_script:
   - ./cc-test-reporter after-build --exit-code $TRAVIS_TEST_RESULT
 branches:
@@ -27,9 +27,9 @@ matrix:
     - rvm: ruby-head
   include:
     - rvm: 2.6
-      env: RUBYOPT="--jit"
+      env: RSPEC_RUBYOPT="--jit"
     - rvm: ruby-head
-      env: RUBYOPT="--jit"
+      env: RSPEC_RUBYOPT="--jit"
 notifications:
   slack:
     secure: 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