$ brew --version
Homebrew 1.3.7-30-gdefd38a
Homebrew/homebrew-core (git revision 989e7; last commit 2017-11-19)

$ pip --version
pip 9.0.1 from /usr/local/lib/python2.7/site-packages (python 2.7)

$ pip install aws-encryption-sdk-cli
Collecting aws-encryption-sdk-cli
  Using cached aws_encryption_sdk_cli-1.1.1-py2.py3-none-any.whl
...
Installing collected packages: aws-encryption-sdk-cli
Exception:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/pip/basecommand.py", line 215, in main
    status = self.run(options, args)
  File "/usr/local/lib/python2.7/site-packages/pip/commands/install.py", line 342, in run
    prefix=options.prefix_path,
  File "/usr/local/lib/python2.7/site-packages/pip/req/req_set.py", line 784, in install
    **kwargs
  File "/usr/local/lib/python2.7/site-packages/pip/req/req_install.py", line 851, in install
    self.move_wheel_files(self.source_dir, root=root, prefix=prefix)
  File "/usr/local/lib/python2.7/site-packages/pip/req/req_install.py", line 1064, in move_wheel_files
    isolated=self.isolated,
  File "/usr/local/lib/python2.7/site-packages/pip/wheel.py", line 377, in move_wheel_files
    clobber(source, dest, False, fixer=fixer, filter=filter)
  File "/usr/local/lib/python2.7/site-packages/pip/wheel.py", line 323, in clobber
    shutil.copyfile(srcfile, destfile)
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 83, in copyfile
    with open(dst, 'wb') as fdst:
IOError: [Errno 13] Permission denied: '/usr/local/CHANGELOG.rst'