<p>I tried to perform an upgrade install, but without updating MySQL. I am using a combined keyboard/trackball that has rather poor mouse buttons, and I inadvertently clicked twice just before the "SQL" panel in the install, and so skipped over it. I then selected "Previous" to return to the SQL panel so that I could deselect the update of SQL. That was OK, but when I arrived at the summary panel before starting installation, SQL was still selected for update.</p>

<p>I exited the install and restarted it, this time taking care to stop at the "SQL" panel to deselect SQL update, and when I arrived at the summary panel, SQL was not selected for update.</p>

<p>So it seems that the act of going backwards in the install process to deselect SQL did not in fact deselect SQL.</p>