prepare_tempfile_object(): new function, extracted from create_tempfile()
prepare_tempfile_object(): new function, extracted from create_tempfile()

This makes the next step easier.

The old code used to use "path" to set the initial length of
tempfile->filename. This was not helpful because path was usually
relative whereas the value stored to filename will be absolute. So
just initialize the length to 0.

Signed-off-by: Michael Haggerty <c24c152f145c57791e809b126db9e61bd1c1782d@alum.mit.edu>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git