print Travis variable names also for pre-release

Author: Vladimir Kotal

.travis.yml

@@ -36,8 +36,8 @@ deploy:
   # Pre-release
   - provider: releases
     script:
-    - echo "$TRAVIS_TAG"
-    - echo "$TRAVIS_BRANCH"
+    - echo "TRAVIS_TAG: $TRAVIS_TAG"
+    - echo "TRAVIS_BRANCH: $TRAVIS_BRANCH"
     - mvn -DskipTests=true -Dmaven.javadoc.skip=false -B -V package
     prerelease: true
     api_key: