Index: wp-admin/includes/upgrade.php
===================================================================
--- wp-admin/includes/upgrade.php	(revision 20239)
+++ wp-admin/includes/upgrade.php	(working copy)
@@ -1568,14 +1568,14 @@
 			case 'unique':
 			case 'key':
 				$validfield = false;
-				$indices[] = trim(trim($fld), ", \n");
+				$indices[] = trim(trim(str_replace('`', '', $fld)), ", \n");
 				break;
 			}
 			$fld = trim($fld);
 
 			// If it's a valid field, add it to the field array
 			if ($validfield) {
-				$cfields[strtolower($fieldname)] = trim($fld, ", \n");
+				$cfields[strtolower($fieldname)] = trim(str_replace('`', '', $fld), ", \n");
 			}
 		}