git-serve: Fix pkgbase_exists()

Fixes a regression introduced in 8c87b1df

 (git-serve: Add support for
setting keywords, 2015-10-22).

Signed-off-by: Mark Weiman <mark.weiman@markzz.com>
Signed-off-by: Lukas Fleischer <lfleischer@archlinux.org>

git-interface/git-serve.py

@@ -37,7 +37,7 @@ def pkgbase_from_name(pkgbase):
     return row[0] if row else None
 
 def pkgbase_exists(pkgbase):
-    return (pkgbase_from_name(pkgbase) > 0)
+    return pkgbase_from_name(pkgbase) is not None
 
 def list_repos(user):
     db = mysql.connector.connect(host=aur_db_host, user=aur_db_user,