setuptools takes long when interrupted with SIGINT during reading a dependency URL

[Karl-Philipp Richter]

steps to reproduce:

  1. create `setup.py` with

        from setuptools import setup, find_packages
        from pkg_resources import parse_version

        setup(
            name = "py-test",
            version = "1.0",
            packages = ["."],
            install_requires = ["wxPython"],
        )
  2. and run `python setup.py build && sudo python setup.py install`
  3. interrupt with <kbd>Ctrl</kbd>+<kbd>C</kbd> right after `Reading https://pypi.python.org/simple/wxPython/` has been written to terminal

The interruption can take up to 10 seconds which is too slow.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: python-setuptools 12.2-1
Uname: Linux 4.1.4-040104-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.3
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Sep 3 21:18:56 2015
Dependencies: python-pkg-resources 12.2-1
InstallationDate: Installed on 2015-06-08 (87 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
PackageArchitecture: all
SourcePackage: python-setuptools
UpgradeStatus: Upgraded to vivid on 2015-06-09 (86 days ago)