Comment 13 for bug 1194841

Between Firefox (and TB) 17 and 18b2 the proxy detection broke for the case of autodetection.
I haven't fully debugged it yet but what happens is that
https://mxr.mozilla.org/mozilla-beta/source/toolkit/system/unixproxy/nsUnixSystemProxySettings.cpp#494 can return NS_ERROR_FAILURE what it does in my usecase where there is no GConf,GSettings and nothing is set in environment variables.

Apparently https://mxr.mozilla.org/mozilla-beta/source/netwerk/base/src/nsProtocolProxyService.cpp#1462 was changed in a way that
https://mxr.mozilla.org/mozilla-beta/source/netwerk/base/src/nsProtocolProxyService.cpp#1552
is still reached and something happens within that evaluation.

When I compare with 17 I find:
https://mxr.mozilla.org/mozilla-release/source/netwerk/base/src/nsProtocolProxyService.cpp#1258

So in my use case if no system proxy was found we left Resolve_Internal via NS_OK immediately instead of proceeding to everything below.

This breaks Necko for me on systems not running with Gnome (no GConf/GSettings) and having default settings for using system proxy settings.