Linux pip package installation error
Seems there's a problem with your pip installation. I have two options for you. 
1) Edit file /usr/lib/python2.7/site-packages/packaging/requirements.py and replace line 
MARKER_EXPR = originalTextFor(MARKER_EXPR())("marker") 
with
MARKER_EXPR = originalTextFor(MARKER_EXPR)("marker")
OR
2) Try and upgrade your pip installation with 
pip install -U pip setuptools
I am using python 2.7 and trying to install scrapy using pip but get this:
Exception:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/pip/basecommand.py", line 215, in main
    status = self.run(options, args)
  File "/usr/local/lib/python2.7/dist-packages/pip/commands/install.py", line 324, in run
    requirement_set.prepare_files(finder)
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 380, in prepare_files
    ignore_dependencies=self.ignore_dependencies))
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 634, in _prepare_file
    abstract_dist.prep_for_dist()
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_set.py", line 129, in prep_for_dist
    self.req_to_install.run_egg_info()
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_install.py", line 412, in run_egg_info
    self.setup_py, self.name,
  File "/usr/local/lib/python2.7/dist-packages/pip/req/req_install.py", line 387, in setup_py
    import setuptools  # noqa
  File "/root/.local/lib/python2.7/site-packages/setuptools/init.py", line 12, in 
    import setuptools.version
  File "/root/.local/lib/python2.7/site-packages/setuptools/version.py", line 1, in 
    import pkg_resources
  File "/root/.local/lib/python2.7/site-packages/pkg_resources/init.py", line 72, in 
    import packaging.requirements
  File "/root/.local/lib/python2.7/site-packages/packaging/requirements.py", line 59, in 
    MARKER_EXPR = originalTextFor(MARKER_EXPR())("marker")
TypeError: call() takes exactly 2 arguments (1 given)