Better error handling of apt-add-repository

[Ma Hsiao-chun]

If I issue "sudo add-apt-repository ppa:ubuntu-wine/ppa" without Internet connected.
I get something like this.

Traceback (most recent call last):
  File "/usr/bin/add-apt-repository", line 125, in <module>
    ppa_info = get_ppa_info_from_lp(user, ppa_name)
  File "/usr/lib/python2.7/dist-packages/softwareproperties/ppa.py", line 80, in get_ppa_info_from_lp
    curl.perform()
pycurl.error: (6, "Couldn't resolve host 'launchpad.net'")

Some other users reported that they got similar things for unknown reasons.
(From http://forum.ubuntu.org.cn/viewtopic.php?t=381149)

Traceback (most recent call last):
File "/usr/bin/add-apt-repository", line 125, in <module>
ppa_info = get_ppa_info_from_lp(user, ppa_name)
File "/usr/lib/python2.7/dist-packages/softwareproperties/ppa.py", line 80, in get_ppa_info_from_lp
curl.perform()
pycurl.error: (7, "couldn't connect to host")

Errors are possible and acceptable.
However, such error messages mentioned above are insane.
Please fix it.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: software-properties-common 0.82.7.2
ProcVersionSignature: Ubuntu 3.2.0-30.48-generic 3.2.27
Uname: Linux 3.2.0-30-generic x86_64
ApportVersion: 2.0.1-0ubuntu13
Architecture: amd64
Date: Thu Sep 20 12:14:21 2012
InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120823.1)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no username)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: software-properties
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Scott Testerman (scott-testerman)]

Agreed that error handling should generally be more graceful. For instance, one is informed when adding a PPA that it is possible to cancel the addition by pressing Ctrl-C, but the result is:

Press [ENTER] to continue or ctrl-c to cancel adding it
^CTraceback (most recent call last):
  File "/usr/bin/apt-add-repository", line 158, in <module>
    sys.stdin.readline()
KeyboardInterrupt

Why not catch the interrupt and simply print an "installation aborted" message?