Deleted source entries remain in /etc/apt/sources.list.d

To reproduce:

1. Open Software Sources window

2. Add a PPA (eg: ppa:ubuntu-wine/ppa)

3. Change distribution version or delete entry

4. Notice that entry is still present in /etc/apt/sources.list.d as a zero-byte file with the initial distribution in the filename.

ProblemType: Bug
Architecture: i386
CheckboxSubmission: b8398b21075a3a8723b2ba20478c4f9e
CheckboxSystem: 703a6ca1eefae989daaf40c6bb6aa94a
Date: Mon Feb 22 20:11:24 2010
DistroRelease: Ubuntu 10.04
InstallationMedia: Ubuntu 10.04 "Lucid Lynx" - Alpha i386 (20091209)
NonfreeKernelModules: ufs qnx4 hfsplus hfs minix ntfs vfat msdos fat jfs xfs exportfs reiserfs rfcomm sco bridge stp bnep binfmt_misc l2cap ppdev arc4 fbcon tileblit font bitblit softcursor vga16fb vgastate iwl3945 iwlcore snd_hda_codec_idt mac80211 i915 sdhci_pci snd_hda_intel snd_hda_codec snd_hwdep snd_pcm_oss snd_mixer_oss dell_wmi sdhci snd_pcm snd_seq_dummy snd_seq_oss joydev ricoh_mmc led_class snd_seq_midi btusb drm_kms_helper dell_laptop cfg80211 bluetooth drm i2c_algo_bit video snd_rawmidi intel_agp snd_seq_midi_event dcdbas snd_seq snd_timer snd_seq_device snd agpgart soundcore snd_page_alloc output usbhid psmouse serio_raw lp parport ohci1394 b44 ssb mii ieee1394
Package: software-properties-gtk 0.75.7
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.utf8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-12.17-genusername
SourcePackage: software-properties
Uname: Linux 2.6.32-12-generic i686