sylius install does not check for GD

log

$ app/console sylius:install -e prod
Installing Sylius.

Checking system requirements.
PHP version and settings
PHP version OK
Recommanded PHP version OK
timezone OK
Deprecated timezone OK
detect_unicode OK
detect_unicode OK
short_open_tag WARNING
magic_quotes_gpc OK
register_globals OK
session.auto_start OK
extensions
JSON OK
Session OK
Ctype OK
Tokenizer OK
SimpleXML OK
APC OK
PCRE OK
PHP-XML OK
Multibyte String OK
Iconv OK
Intl OK
ICU OK
Accelerator WARNING
PDO OK
file system
vendors OK
cache OK
logs OK
parameters.yml OK

Setting up database.
...

prod.log

[2013-12-22 11:53:40] request.INFO: Matched route "_imagine_sylius_90x60" (parameters: "_controller": "liip_imagine.controller:filterAction", "filter": "sylius_90x60", "path": "b5/f7/2ede9aec5ecec0dc4b264a81e3b6.jpeg", "_route": "_imagine_sylius_90x60") [] []
[2013-12-22 11:53:40] security.DEBUG: Read SecurityContext from the session [] []
[2013-12-22 11:53:40] security.DEBUG: Reloading user from user provider. [] []
[2013-12-22 11:53:40] security.DEBUG: Username "admin@admin.com" was reloaded from user provider. [] []
[2013-12-22 11:53:40] request.CRITICAL: Uncaught PHP Exception Imagine\Exception\RuntimeException: "Gd not installed" at /var/www/vendor/imagine/imagine/lib/Imagine/Gd/Imagine.php line 42 {"exception":"[object] (Imagine\\Exception\\RuntimeException: Gd not installed at /var/www/vendor/imagine/imagine/lib/Imagine/Gd/Imagine.php:42)"} []
[2013-12-22 11:53:40] security.DEBUG: Write SecurityContext in the session [] []