Ok, trying with the client, I commented out check_modules() call and there are still errors:

$ python ./setup.py bdist_rpm
...
RPM build errors:
    File listed twice: /usr/share/doc/openerp-client-5.0.0_rc2/CREDITS
    File listed twice: /usr/share/doc/openerp-client-5.0.0_rc2/Changelog
    File listed twice: /usr/share/doc/openerp-client-5.0.0_rc2/INSTALL
    File listed twice: /usr/share/doc/openerp-client-5.0.0_rc2/LICENCE.txt
    File listed twice: /usr/share/doc/openerp-client-5.0.0_rc2/License.rtf
    File listed twice: /usr/share/doc/openerp-client-5.0.0_rc2/README.txt
    Installed (but unpackaged) file(s) found:
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/Calendar.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasDay.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasDayRange.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasEvent.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasEventView.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasGrid.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasHEventView.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasMagnetTable.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasRectangle.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasTable.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasTimeline.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/CanvasVEventView.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/Event.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/Matrix.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/Model.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/MyCalendar.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/TableLayout.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/Calendar/util.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/SpiffGtkWidgets/color.pyo
   /usr/lib/python2.5/site-packages/openerp-client/common/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/common/common.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/action/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/action/main.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/action/wizard.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/main.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/form.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/tree.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/view_sel/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/view_tree/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/view_tree/parse.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/view_tree/view_tree.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/view_tree/view_tree_sc.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/win_export.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/win_extension.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/win_import.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/win_list.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/win_preference.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/win_search.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/gui/window/win_selection.pyo
   /usr/lib/python2.5/site-packages/openerp-client/modules/spool/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/observator.pyo
   /usr/lib/python2.5/site-packages/openerp-client/openerp-client.pyo
   /usr/lib/python2.5/site-packages/openerp-client/options.pyo
   /usr/lib/python2.5/site-packages/openerp-client/plugins/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/plugins/workflow_print/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/printer/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/printer/printer.pyo
   /usr/lib/python2.5/site-packages/openerp-client/release.pyo
   /usr/lib/python2.5/site-packages/openerp-client/rpc.pyo
   /usr/lib/python2.5/site-packages/openerp-client/service.pyo
   /usr/lib/python2.5/site-packages/openerp-client/signal_event.pyo
   /usr/lib/python2.5/site-packages/openerp-client/tiny_socket.pyo
   /usr/lib/python2.5/site-packages/openerp-client/tinygraph/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/tools/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/tools/datetime_util.pyo
   /usr/lib/python2.5/site-packages/openerp-client/tools/debug.pyo
   /usr/lib/python2.5/site-packages/openerp-client/tools/win32.pyo
   /usr/lib/python2.5/site-packages/openerp-client/translate.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/model/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/model/field.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/model/group.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/model/record.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/screen/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/screen/screen.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/calendar.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/calendar_gtk/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/calendar_gtk/parser.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/calendar_gtk/parser_dummy.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/action.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/binary.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/button.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/calendar.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/char.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/checkbox.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/date_widget.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/float_time.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/image.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/interface.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/many2many.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/many2one.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/one2many_list.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/parser.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/picture.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/progressbar.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/reference.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/selection.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/spinbutton.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/spinint.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/textbox.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/textbox_tag.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/url.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/form_gtk/wid_common.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/gantt.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/gantt_gtk/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/gantt_gtk/parser_dummy.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/graph.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/graph_gtk/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/graph_gtk/graph.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/graph_gtk/parser.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/interface.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/list.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/screen_container.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/tree_gtk/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/tree_gtk/date_renderer.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/tree_gtk/decoratedtree.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/tree_gtk/editabletree.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/tree_gtk/parser.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget/view/widget_parse.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/__init__.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/calendar.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/char.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/checkbox.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/date_widget.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/form.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/reference.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/selection.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/spinbutton.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/spinint.pyo
   /usr/lib/python2.5/site-packages/openerp-client/widget_search/wid_int.pyo
error: command 'rpmbuild' failed with exit status 1
[openerp-client-5.0.0_rc2]$