Adding the following Test Coverage:

Use mysql_user module to create, delete users.
Update user password and ensure new password was updated for the correct user.
Assert user has access to multiple databases
Assert user creation, deleting using different user privilege and ensure privilege work correctly.

database/mysql_user

@@ -209,7 +209,8 @@ def user_mod(cursor, user, host, password, new_priv, append_privs):
         for db_table in db_table_intersect:
             priv_diff = set(new_priv[db_table]) ^ set(curr_priv[db_table])
             if (len(priv_diff) > 0):
-                privileges_revoke(cursor, user,host,db_table,grant_option)
+                if not append_privs:
+                    privileges_revoke(cursor, user,host,db_table,grant_option)
                 privileges_grant(cursor, user,host,db_table,new_priv[db_table])
                 changed = True