ERROR: ...bin/strip %swbepm

[Aleksey Cheusov <cheusov%tut.by@localhost>]

My package fails at 'install' stage with the following error messages.

  => Checking for work-directory references in epm-4.1
  ERROR: /usr/pkg/bin/epm:        /tmp/obj_pkgsrc/wip/epm/work/.tools/bin/strip 
%swbepm: Unable to create "%s" -
  ERROR: *** The above files still have references to the build directory.
  ERROR:     This is possibly an error that should be fixed by unwrapping
  ERROR:     the files or adding missing tools to the package makefile!
  *** Error code 1

It's not clear for me what's wrong.
Can anybody decode the above?

-- 
Best regards, Aleksey Cheusov.