Error in roscore, rospkg==1.1.0 distibution not found. I have 1.1.0-1 installed

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Traceback (most recent call last):
File "/home/saurabh/.local/bin/rosversion", line 4, in <module>
__import__('pkg_resources').run_script('rospkg==1.1.0', 'rosversion')
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2927, in <module>
@_call_aside
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2913, in _call_aside
f(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2940, in _initialize_master_working_set
working_set = WorkingSet._build_master()
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 635, in _build_master
ws.require(__requires__)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 943, in require
needed = self.resolve(parse_requirements(requirements))
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 829, in resolve
raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'rospkg==1.1.0' distribution was not found and is required by the application
Invalid <param> tag: Cannot load command parameter [rosversion]: command [rosversion roslaunch] returned with code [1].

Param xml is <param command="rosversion roslaunch" name="rosversion"/>
The traceback for the exception was written to the log file