minor #18962 [travis] Don't use parallel on HHVM (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
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[travis] Don't use parallel on HHVM

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Targeting a speedup of the HHVM matrix line especially.

Commits
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346149e [travis] Don't use parallel on HHVM

.travis.yml

@@ -39,6 +39,7 @@ cache:
 services: mongodb
 
 before_install:
+    - stty cols 120
     - PHP=$TRAVIS_PHP_VERSION
     # Matrix lines for intermediate PHP versions are skipped for pull requests
     - if [[ ! $deps && ! $PHP = ${MIN_PHP%.*} && ! $PHP = hhvm* && $TRAVIS_PULL_REQUEST != false ]]; then deps=skip; skip=1; fi
@@ -76,8 +77,9 @@ install:
 
 script:
     - if [[ $skip ]]; then echo -e "\\n\\e[1;34mIntermediate PHP version $PHP is skipped for pull requests.\\e[0m"; fi
-    - if [[ ! $deps ]]; then echo "$COMPONENTS" | parallel --gnu '$PHPUNIT --exclude-group tty,benchmark,intl-data {}'; fi
-    - if [[ ! $deps ]]; then echo -e "\\nRunning tests requiring tty"; $PHPUNIT --group tty; fi
+    - if [[ ! $deps && ! $PHP = hhvm* ]]; then echo "$COMPONENTS" | parallel --gnu '$PHPUNIT --exclude-group tty,benchmark,intl-data {}'; fi
+    - if [[ ! $deps && ! $PHP = hhvm* ]]; then echo -e "\\nRunning tests requiring tty"; $PHPUNIT --group tty; fi
+    - if [[ ! $deps && $PHP = hhvm* ]]; then $PHPUNIT --exclude-group benchmark,intl-data; fi
     - if [[ ! $deps && $PHP = ${MIN_PHP%.*} ]]; then echo -e "1\\n0" | xargs -I{} sh -c 'echo "\\nPHP --enable-sigchild enhanced={}" && ENHANCE_SIGCHLD={} php-$MIN_PHP/sapi/cli/php .phpunit/phpunit-4.8/phpunit --colors=always src/Symfony/Component/Process/'; fi
     - if [[ $deps = high ]]; then echo "$COMPONENTS" | parallel --gnu -j10% 'cd {}; composer update --no-progress --ansi; $PHPUNIT --exclude-group tty,benchmark,intl-data'$LEGACY; fi
     - if [[ $deps = low ]]; then echo "$COMPONENTS" | parallel --gnu -j10% 'cd {}; composer update --no-progress --ansi --prefer-lowest --prefer-stable; $PHPUNIT --exclude-group tty,benchmark,intl-data'; fi