There is nothing in the code that handles raw prints on windows that cleans up the received file, neither on success nor failure.
Fixed in commit 29064.
Updated in commit 29070.
Looks good, verified with a Windows 7 client using build 4510.
The resulting printout from these commands where slightly different as expected and the temporary file was deleted in both cases:
lpr -o raw testfile -P thinlocal
lpr testfile -P thinlocal