Firefox says I am using proxy after update

[Fikrul Arif]

After updating Firefox, I can't connect to the internet. It said that the connection cannot be established with the proxy set. I'd checked Firefox settings, "Use system proxy settings" was checked and the system is not set any proxy. I've confirmed it by checking System Settings -> Network and running `set | grep proxy`. I could connect to the internet again after setting Firefox proxy to "No proxy" rather than "Use system proxy settings".

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: firefox 22.0+build2-0ubuntu0.13.04.1
ProcVersionSignature: Ubuntu 3.8.0-25.37-generic 3.8.13
Uname: Linux 3.8.0-25-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.9.2-0ubuntu8.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: fikr4n 2170 F.... pulseaudio
BuildID: 20130620122336
Channel: Unavailable
Date: Tue Jul 2 12:52:57 2013
ForcedLayersAccel: False
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2012-11-04 (239 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
IpRoute:
 default via 192.168.1.1 dev wlan0 proto static
 169.254.0.0/16 dev wlan0 scope link metric 1000
 192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.116 metric 9
MarkForUpload: True
MostRecentCrashID: bp-f16709cd-368b-4075-be71-fc8b02130429
PrefSources: prefs.js
Profiles: Profile0 (Default) - LastVersion=22.0/20130620122336 (In use)
RelatedPackageVersions:
 gnome-shell 3.6.3.1-0ubuntu6
 icedtea-7-plugin 1.3.2-1ubuntu1
 totem-mozilla 3.6.3-0ubuntu6
 rhythmbox-mozilla 2.98-0ubuntu5
RunningIncompatibleAddons: False
SourcePackage: firefox
SubmittedCrashIDs: bp-f16709cd-368b-4075-be71-fc8b02130429
UpgradeStatus: Upgraded to raring on 2013-05-13 (50 days ago)
dmi.bios.date: 01/18/2012
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: F.01
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: 183A
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 56.0E
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnHewlett-Packard:bvrF.01:bd01/18/2012:svnHewlett-Packard:pnHPPaviliong4NotebookPC:pvr0791100000205610000620100:rvnHewlett-Packard:rn183A:rvr56.0E:cvnHewlett-Packard:ct10:cvrChassisVersion:
dmi.product.name: HP Pavilion g4 Notebook PC
dmi.product.version: 0791100000205610000620100
dmi.sys.vendor: Hewlett-Packard