Fixed one typo in response_helpers which caused is_admin context variable not to work correctly.
Created new checkLinkNameForId function that checks if link_name is correct when creating new user and modifying existing one. This is now used for validation instead of doesLinkNameBelongToId in UserForm clean_link_name function. The previous validation function didn't allow to create new users and modify linkname of existing ones. Additionally I created new doesLinkNameExist helper function.
<html>
<head></head>
<body>
<h1>Django Internal Tests: Login</h1>
{% if form.has_errors %}
<p>Your username and password didn't match. Please try again.</p>
{% endif %}
<form method="post" action=".">
<table>
<tr><td><label for="id_username">Username:</label></td><td>{{ form.username }}</td></tr>
<tr><td><label for="id_password">Password:</label></td><td>{{ form.password }}</td></tr>
</table>
<input type="submit" value="login" />
<input type="hidden" name="next" value="{{ next }}" />
</form>
</body>
</html>