Fixed crash and description for digest authentication

Crash happens when mixing authenticated and non-authenticated requests. For me it crashed only with chrome and ssl. (chrome probably requesting more connections and ssl probably allocating memory that then gets double freed)

	127.0.0.1 - test [19/Mar/2013:17:27:32 W. Europe Standard Time] "GET /index_co.xhtml HTTP/1.1" 200 1904 - "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.172 Safari/537.22"
	127.0.0.1 - test [19/Mar/2013:17:27:32 W. Europe Standard Time] "GET /d3.js HTTP/1.1" 200 268364 "https://127.0.0.1/index_co.xhtml" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.172 Safari/537.22"
	127.0.0.1 - test [19/Mar/2013:17:27:33 W. Europe Standard Time] "GET /favicon.ico HTTP/1.1" 404 35 - "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.172 Safari/537.22"
	127.0.0.1 - - [19/Mar/2013:17:27:34 W. Europe Standard Time] "GET /ajax/current_data.json HTTP/1.1" -1 0 "https://127.0.0.1/index_co.xhtml" "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.172 Safari/537.22"

global_auth_file was set but: /ajax/current_data.json is generated through the callback, thus has no remote user yet.