[Bug-tar] tar update and change directory option does not seem to work

[Rome Was not build on a day]

Can an existing tar file be updated from another directory using update (-u)
and change directory (-C) option.

For directory structure

mydir/
mydir/test
mydir/test/subtest/1.txt

commands
    $ cd mydir
    $ tar -uf test.tar -C test subtest
    --> this works
    -->next run of this
    $ tar -uf test.tar -C test subtest
    ----> this fails

    /bin/tar: subtest/1.txt: Cannot stat: No such file or directory
    /bin/tar: Exiting with failure status due to previous errors



also asked on stackoverflow without answerw
http://stackoverflow.com/questions/7533608/tar-update-and-change-directory-option-does-not-seem-to-work