fix(Travis): Fix PRs from forks triggering semantic release travis job (

#39)

.travis.yml

@@ -10,6 +10,7 @@ script: py.test
 jobs:
   include:
     - stage: release
+      if: branch = master AND type = push AND fork = false
       language: python
       python:
         - '3.6'
@@ -21,9 +22,8 @@ jobs:
         - secure: 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
       install: skip
       script:
-      - export BRANCH=$(if [ "$TRAVIS_PULL_REQUEST" == "false" ]; then echo $TRAVIS_BRANCH; else echo $TRAVIS_PULL_REQUEST_BRANCH; fi)
       - git config --global user.name "semantic-release (via TravisCI)"
       - git config --global user.email "semantic-release@travis"
-      - if [ "$BRANCH" == "master" ]; then pip install python-semantic-release; fi
-      - if [ "$BRANCH" == "master" ]; then semantic-release publish; fi
+      - pip install python-semantic-release;
+      - semantic-release publish;