souphttpsrc error handling doesn't differentiate "password needed"

Submitted by Bastien Nocera @hadess

Link to original bug (#744996)

Description

In cf31a428, souphttpsrc starting sending NOT_AUTHORIZED when 401, 402, 403 and 407 HTTP codes are sent back. 401 and 407 are the only ones that should trigger password prompts, but there's no way to differentiate them.

Version: 1.x