Fixed Broken PIPE Error

[srinivasreddy]

• When pip is piped just do the signal default behaviour

[srinivasreddy]

Fix for the issue #3263. However, i am not really sure whether call signal function at the module level or in function - main. @xavfernandez @pfmoore feedback appreciated

[xavfernandez]

Well the default action for SIGPIPE seems to be to kill the process.
It is quite ok for pip list but less ok for pip install.

Currently pip install django | grep -q django spits identical errors as in #3263 but ends up installing django.

With SIG_DFL this is not the case anymore.