UnicodeDecodeError on Bench installation

Hi, I am trying to install erpnext. but i am getting following while running the command pip install --user -e bench-repo.
Can anyone help me?

Traceback (most recent call last):
File “/usr/lib/python2.7/dist-packages/pip/basecommand.py”, line 122, in main
status = self.run(options, args)
File “/usr/lib/python2.7/dist-packages/pip/commands/install.py”, line 278, in run
requirement_set.prepare_files(finder, force_root_egg_info=self.bundle, bundle=self.bundle)
File “/usr/lib/python2.7/dist-packages/pip/req.py”, line 1198, in prepare_files
File “/usr/lib/python2.7/dist-packages/pip/req.py”, line 1376, in unpack_url
File “/usr/lib/python2.7/dist-packages/pip/download.py”, line 582, in unpack_http_url
unpack_file(temp_location, location, content_type, link)
File “/usr/lib/python2.7/dist-packages/pip/util.py”, line 643, in unpack_file
untar_file(filename, location)
File “/usr/lib/python2.7/dist-packages/pip/util.py”, line 574, in untar_file
path = os.path.join(location, fn)
File “/usr/lib/python2.7/posixpath.py”, line 80, in join
path += ‘/’ + b
UnicodeDecodeError: ‘ascii’ codec can’t decode byte 0xc5 in position 19: ordinal not in range(128)

Storing debug log for failure in /home/frappe/.pip/pip.log

You can also use this option (I find this way works best)

sudo pip install -e bench-repo.

Thank you for reply. I have run following commmand: sudo pip install -e bench-repo, and
getting following error.

frappe@LatitudeE5400:~$ sudo pip install -e bench-repo
Traceback (most recent call last):
File “/usr/bin/pip”, line 11, in
AttributeError: ‘module’ object has no attribute ‘_main’