Makefile | 4 3 + 1 - 0 !
1 file changed, 3 insertions(+), 1 deletion(-)

---

cupsconnection.c | 20 13 + 7 - 0 !
cupsmodule.c | 32 19 + 13 - 0 !
2 files changed, 32 insertions(+), 20 deletions(-)

 prevent auth loops by returning null when the callback returns an empty string.

Also add support for the callback returning None when it wants to
cancel the current operation.