Bug #29236 Using Manage role in web admin backoffice results thrown an exception

Description:
Web admin interface to manage roles throw an exception while trying to set a role to a user.

The problem occurs not to give a role to a user displayed on the list after having selected a role, but while cliking on one of the top letters that are supposed to filter the user list.

How to repeat:
Try to manage the roles by the link "Manage Role" in the ASP Web backoffice (to configure asp application)

You have a list of roles that is displayed. Choose One.

Now a list of users should be displayed with a range of letter A - Z at the top.

Chosse a Letter.

Exception occur.

An exception occurred. Please check the Event Log. à System.Web.Administration.WebAdminPage.CallWebAdminHelperMethod(Boolean isMembership, String methodName, Object[] parameters, Type[] paramTypes) à System.Web.Administration.WebAdminPage.RetrieveLetter(Object sender, RepeaterCommandEventArgs e, GridView dataGrid, String all, MembershipUserCollection users) à System.Web.Administration.WebAdminPage.RetrieveLetter(Object sender, RepeaterCommandEventArgs e, GridView dataGrid, String all) à ASP.security_roles_managesinglerole_aspx.RetrieveLetter(Object sender, RepeaterCommandEventArgs e) à System.Web.UI.WebControls.Repeater.OnItemCommand(RepeaterCommandEventArgs e) à System.Web.UI.WebControls.Repeater.OnBubbleEvent(Object sender, EventArgs e) à System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) à System.Web.UI.WebControls.RepeaterItem.OnBubbleEvent(Object source, EventArgs e) à System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) à System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) à System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) à System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) à System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) à System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) à System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/29329

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/29329

Fixed in 5.1.3

A note has been added to the 5.1.3 changelog: 

An exception would be thrown when using the Manage Role functionality within the web administrator to assign a role to a user