AppVeyor: Try to fix tests

appveyor.yml

@@ -8,6 +8,7 @@ skip_commits:
     message: /.*\[skip appveyor\].*/
 
 cache:
+    - c:\projects\asynctweetsbundle\composer.phar
     - c:\tools\php -> appveyor.yml
     - '%LOCALAPPDATA%\Composer\files'
 
@@ -34,8 +35,10 @@ install:
     - IF %PHP%==1 echo @php %%~dp0composer.phar %%* > composer.bat
     - appveyor DownloadFile https://getcomposer.org/composer.phar
     - cd c:\projects\asynctweetsbundle
-    - composer require --dev "symfony/symfony:2.8.*" --no-update
-    - composer install --no-interaction -vv --profile --no-progress
+    - IF NOT EXIST composer.phar (appveyor DownloadFile https://getcomposer.org/download/1.2.1/composer.phar)
+    - php composer.phar require --dev "symfony/symfony:2.8.*" --no-update
+    - php composer.phar install --no-interaction -vv --profile --no-progress --ansi
+    - SET COMPOSER_ROOT_VERSION=
 
 test_script:
     - cd c:\projects\asynctweetsbundle