title: How to create python2.7 environment by virtualenv?
body: <p>I am using python on MacOS and I have a problem to setup a python2.7 environment. I have installed both python2.7 and python3.6 on the system. And run below code to setup python2.7 env. I am not sure why I get this error. From the output I see it is using <code>/anaconda/lib/python3.6</code> directory. How can I make it to use <code>python2.7</code> environment?</p>
  
  <pre><code>$ virtualenv --python=/usr/bin/python2.7 venv/
  Running virtualenv with interpreter /usr/bin/python2.7
  New python executable in /Users/joey/dev/jump/jump-api/venv/bin/python2.7
  Traceback (most recent call last):
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 2869, in &lt;module&gt;
      main()
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 713, in main
      symlink=options.symlink)
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 925, in create_environment
      site_packages=site_packages, clear=clear, symlink=symlink))
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 1231, in install_python
      copy_exe_shared_libs_and_symlinks(executable, py_executable, home_dir)
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 2828, in copy_exe_shared_libs_and_symlinks
      of = codefile(f, rpaths)
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 2799, in codefile
      return machofile(file, list(initial_rpaths_transitive))
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 2422, in __init__
      _, sos = zip(*mach_o_find_dylibs(file))
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 2386, in mach_o_find_dylibs
      do_file(ofile, find_lc_load_dylib, offset_size(), results, regex)
    File "/anaconda/lib/python3.6/site-packages/virtualenv.py", line 2355, in do_file
      do_file(file, offset_size(offset, size), *args)
  TypeError: do_file() takes at least 4 arguments (3 given)
  </code></pre>