Check if xdebug is enabled before attempting to disable it.

Author: weierophinney

.travis.yml

@@ -56,7 +56,7 @@ matrix:
     - php: 7.2
 
 before_install:
-  - if [[ $TEST_COVERAGE != 'true' ]]; then phpenv config-rm xdebug.ini || return 0 ; fi
+  - if [[ $TEST_COVERAGE != 'true' && "$(php --version | grep xdebug -ci)" -ge 1 ]]; then phpenv config-rm xdebug.ini || return 0 ; fi
   - travis_retry composer self-update
 
 install: