code: def get_file_content(url, comes_from=None):
      
      match = _scheme_re.search(url)
      if match:
          scheme = match.group(1).lower()
          if (scheme == 'file' and comes_from
              and comes_from.startswith('http')):
              raise InstallationError(
                  'Requirements file %s references URL %s, which is local'
                  % (comes_from, url))
          if scheme == 'file':
              path = url.split(':', 1)[1]
              path = path.replace('\\', '/')
              match = _url_slash_drive_re.match(path)
              if match:
                  path = match.group(1) + ':' + path.split('|', 1)[1]
              path = urllib.unquote(path)
              if path.startswith('/'):
                  path = '/' + path.lstrip('/')
              url = path
          else:
              ## FIXME: catch some errors
              resp = urlopen(url)
              return geturl(resp), resp.read()
      try:
          f = open(url)
          content = f.read()
      except IOError:
          e = sys.exc_info()[1]
          raise InstallationError('Could not open requirements file: %s' % str(e))
      else:
          f.close()
      return url, content
docs: Gets the content of a file; it may be a filename, file: URL, or
      http: URL.  Returns (location, content)