lupdate can't find some headers in certain circumstances

When invoking lupdate from the command line like the example below[1] you receive the message "[..]Qualifying with unknown namespace/class[..]" because lupdate can't find the associated header file (.h) to a source file (cpp) containing the 'tr' macro. This occurs because the source file includes the header file relatively to the 'include directives' (-I), using the form with brackets: <header.h>. lupdate doesn't look for the header file from the project file (.pro) directory but from the current directory. I guess it's a bug because in complex projects when there is some project file dependencies there is no way to solve this issue.

[1]:

 lupdate directoy/my_project.pro