I run into problem while using $specific_where variable for my plugin. If user has access to only one project (or if there is only one project in bug tracker), $specific_where contains wrong value. It is used in number of places in Mantis - so this touches not only my plugin.

$specific_where is helper_project_specific_where() [helper_api.php]
This one is calling user_get_all_accessible_projects() [user_api.php] and have:

...
if( 0 == count( $t_project_ids ) ) {
$t_project_filter = ' 1<>1';
} else if( 1 == count( $t_project_ids ) ) {
$t_project_filter = ' project_id=' . $t_project_ids[0];
} else {
$t_project_filter = ' project_id IN (' . join( ',', $t_project_ids ) . ')';
}
...

Please look on this line:
$t_project_filter = ' project_id=' . $t_project_ids[0];

It assumes that the project is first element in array. Now lets look at user_get_all_accessible_projects(). In the case of "All projects", thee following code works:

...

Create a combined array where key = value

$t_project_ids = array_combine( $t_topprojects, $t_topprojects );
...

Then function returns $t_project_ids. Thus if "the only" project_id is, for example, 3 then key is also 3 and $t_project_ids[0] is naturally empty. As effect "} else if( 1 == count( $t_project_ids ) ) {" condition from above will work, but $t_project_filter will contain something like "project_id=" -> value is missing at the end.