freebsd stable - Jan 2016 - make installworld creates empty dirs which are deleted by make delete-old

I updated the server 3 times in one week (to 10.2-p8, -p9, -p10).

make check-old lists these directories on each update

# make check-old
 >>> Checking for old files
 >>> Checking for old libraries
 >>> Checking for old directories
/usr/include/atf-c
/usr/include/atf-c++
/usr/share/atf
/usr/share/doc/atf
To remove old files and directories run 'make delete-old'.
To remove old libraries run 'make delete-old-libs'.

Those directories were deleted by delete-old

# make -DBATCH_DELETE_OLD_FILES delete-old
 >>> Removing old files (only deletes safe to delete libs)
 >>> Old files removed
 >>> Removing old directories
/usr/share/doc/atf
/usr/share/atf
/usr/include/atf-c++
/usr/include/atf-c
 >>> Old directories removed
To remove old libraries run 'make delete-old-libs'.

By after next installworld, they are back.

I think there is some bug (leftover) in make install / mtree or 
something like this and those directories should not be created any more.

Miroslav Lachman