old_contents: from __future__ import absolute_import, division, print_function
  
  import os
  import sys
  from os.path import isfile, join, expanduser
  
  import conda.config as cc
  from conda_build.config import config
  
  def find_executable(executable):
      if sys.platform == 'win32':
          dir_paths = [join(config.build_prefix, 'Scripts'),
                       join(cc.root_dir, 'Scripts'),
                       'C:\\cygwin\\bin']
      else:
          dir_paths = [join(config.build_prefix, 'bin'),
                       join(cc.root_dir, 'bin'),]
  
      dir_paths.extend(os.environ['PATH'].split(os.pathsep))
  
      for dir_path in dir_paths:
          if sys.platform == 'win32':
              for ext in  '.exe', '.bat', '':
                  path = join(dir_path, executable + ext)
                  if isfile(path):
                      return path
          else:
              path = join(dir_path, executable)
              if isfile(expanduser(path)):
                  return expanduser(path)
      return None
  
new_contents: from __future__ import absolute_import, division, print_function
  
  import os
  import sys
  from os.path import isfile, join, expanduser
  
  import conda.config as cc
  from conda_build.config import config
  
  def find_executable(executable):
      # dir_paths is referenced as a module-level variable 
      #  in other code
      global dir_paths
      if sys.platform == 'win32':
          dir_paths = [join(config.build_prefix, 'Scripts'),
                       join(cc.root_dir, 'Scripts'),
                       'C:\\cygwin\\bin']
      else:
          dir_paths = [join(config.build_prefix, 'bin'),
                       join(cc.root_dir, 'bin'),]
  
      dir_paths.extend(os.environ['PATH'].split(os.pathsep))
  
      for dir_path in dir_paths:
          if sys.platform == 'win32':
              for ext in  '.exe', '.bat', '':
                  path = join(dir_path, executable + ext)
                  if isfile(path):
                      return path
          else:
              path = join(dir_path, executable)
              if isfile(expanduser(path)):
                  return expanduser(path)
      return None
  
subject: Fix error message when patch is missing.