NOBUG: Change travis.yml back to master

Author: stronk7

.travis.yml

@@ -206,7 +206,7 @@ before_script:
         # We need the official upstream for comparison
         git remote add upstream https://github.com/moodle/moodle.git;
 
-        git fetch upstream MOODLE_39_STABLE;
+        git fetch upstream master;
         export GIT_PREVIOUS_COMMIT="`git merge-base FETCH_HEAD $TRAVIS_COMMIT`";
         export GIT_COMMIT="$TRAVIS_COMMIT";
         export UPSTREAM_FETCH_HEAD=`git rev-parse FETCH_HEAD`