Gracefully disable the mysql module if MySQLdb isn't available

salt/modules/mysql.py

@@ -14,11 +14,17 @@ might look like::
 You can also use a defaults file::
 
     mysql.default_file: '/etc/mysql/debian.cnf'
+
+Required python modules: MySQLdb
 '''
 
 import logging
+try:
     import MySQLdb
     import MySQLdb.cursors
+    has_mysqldb = True
+except ImportError:
+    has_mysqldb = True
 
 log = logging.getLogger(__name__)
 __opts__ = {}
@@ -28,6 +34,7 @@ def __virtual__():
     Only load this module if the mysql config is set
     '''
     if any(k.startswith('mysql.') for k in __opts__.keys()):
+        if has_mysqldb:
             return 'mysql'
     return False