See http://getcomposer.org/doc/articles/troubleshooting.md#package-not-found-on-travis-ci-org.

Author: whatthejeff

.travis.yml

@@ -5,7 +5,7 @@ php:
     - 5.4
 
 before_script:
-    - composer install --dev --prefer-source
+    - COMPOSER_ROOT_VERSION=dev-master composer install --dev --prefer-source
 
 script: vendor/bin/phpunit --configuration ./build/travis-ci.xml
 
@@ -14,4 +14,4 @@ notifications:
   irc:
     channels:
       - "irc.freenode.org#phpunit"
-    use_notice: true
+    use_notice: true