Use os.remove instead of shutil.rmtree if we try to remove a symbolic link

If we try to remove a symbolic link to a directory with shutil.rmtree, we get
the error “Cannot call rmtree on a symbolic link”

IPython/html/nbextensions.py

@@ -1,265 +1,265 b''
 # coding: utf-8
 """Utilities for installing Javascript extensions for the notebook"""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 from __future__ import print_function
 
 import os
 import shutil
 import tarfile
 import zipfile
 from os.path import basename, join as pjoin
 
 # Deferred imports
 try:
     from urllib.parse import urlparse  # Py3
     from urllib.request import urlretrieve
 except ImportError:
     from urlparse import urlparse
     from urllib import urlretrieve
 
 from IPython.utils.path import get_ipython_dir, ensure_dir_exists
 from IPython.utils.py3compat import string_types, cast_unicode_py2
 from IPython.utils.tempdir import TemporaryDirectory
 
 
 def _should_copy(src, dest, verbose=1):
     """should a file be copied?"""
     if not os.path.exists(dest):
         return True
     if os.stat(dest).st_mtime < os.stat(src).st_mtime:
         if verbose >= 2:
             print("%s is out of date" % dest)
         return True
     if verbose >= 2:
         print("%s is up to date" % dest)
     return False
 
 
 def _maybe_copy(src, dest, verbose=1):
     """copy a file if it needs updating"""
     if _should_copy(src, dest, verbose):
         if verbose >= 1:
             print("copying %s -> %s" % (src, dest))
         shutil.copy2(src, dest)
 
 
 def _safe_is_tarfile(path):
     """safe version of is_tarfile, return False on IOError"""
     try:
         return tarfile.is_tarfile(path)
     except IOError:
         return False
 
 
 def check_nbextension(files, ipython_dir=None):
     """Check whether nbextension files have been installed
     
     files should be a list of relative paths within nbextensions.
     
     Returns True if all files are found, False if any are missing.
     """
     ipython_dir = ipython_dir or get_ipython_dir()
     nbext = pjoin(ipython_dir, u'nbextensions')
     # make sure nbextensions dir exists
     if not os.path.exists(nbext):
         return False
     
     if isinstance(files, string_types):
         # one file given, turn it into a list
         files = [files]
     
     return all(os.path.exists(pjoin(nbext, f)) for f in files)
 
 
 def install_nbextension(files, overwrite=False, symlink=False, ipython_dir=None, verbose=1):
     """Install a Javascript extension for the notebook
     
     Stages files and/or directories into IPYTHONDIR/nbextensions.
     By default, this compares modification time, and only stages files that need updating.
     If `overwrite` is specified, matching files are purged before proceeding.
     
     Parameters
     ----------
     
     files : list(paths or URLs)
         One or more paths or URLs to existing files directories to install.
         These will be installed with their base name, so '/path/to/foo'
         will install to 'nbextensions/foo'.
         Archives (zip or tarballs) will be extracted into the nbextensions directory.
     overwrite : bool [default: False]
         If True, always install the files, regardless of what may already be installed.
     symlink : bool [default: False]
         If True, create a symlink in nbextensions, rather than copying files.
         Not allowed with URLs or archives. Windows support for symlinks requires
         Vista or above, Python 3, and a permission bit which only admin users
         have by default, so don't rely on it.
     ipython_dir : str [optional]
         The path to an IPython directory, if the default value is not desired.
         get_ipython_dir() is used by default.
     verbose : int [default: 1]
         Set verbosity level. The default is 1, where file actions are printed.
         set verbose=2 for more output, or verbose=0 for silence.
     """
     
     ipython_dir = ipython_dir or get_ipython_dir()
     nbext = pjoin(ipython_dir, u'nbextensions')
     # make sure nbextensions dir exists
     ensure_dir_exists(nbext)
     
     if isinstance(files, string_types):
         # one file given, turn it into a list
         files = [files]
     
     for path in map(cast_unicode_py2, files):
         
         if path.startswith(('https://', 'http://')):
             if symlink:
                 raise ValueError("Cannot symlink from URLs")
             # Given a URL, download it
             with TemporaryDirectory() as td:
                 filename = urlparse(path).path.split('/')[-1]
                 local_path = os.path.join(td, filename)
                 if verbose >= 1:
                     print("downloading %s to %s" % (path, local_path))
                 urlretrieve(path, local_path)
                 # now install from the local copy
                 install_nbextension(local_path, overwrite, symlink, ipython_dir, verbose)
             continue
         
         # handle archives
         archive = None
         if path.endswith('.zip'):
             archive = zipfile.ZipFile(path)
         elif _safe_is_tarfile(path):
             archive = tarfile.open(path)
         
         if archive:
             if symlink:
                 raise ValueError("Cannot symlink from archives")
             if verbose >= 1:
                 print("extracting %s to %s" % (path, nbext))
             archive.extractall(nbext)
             archive.close()
             continue
         
         dest = pjoin(nbext, basename(path))
         if overwrite and os.path.exists(dest):
             if verbose >= 1:
                 print("removing %s" % dest)
-            if os.path.isdir(dest):
+            if os.path.isdir(dest) and not os.path.islink(dest):
                 shutil.rmtree(dest)
             else:
                 os.remove(dest)
         
         if symlink:
             path = os.path.abspath(path)
             if not os.path.exists(dest):
                 if verbose >= 1:
                     print("symlink %s -> %s" % (dest, path))
                 os.symlink(path, dest)
             continue
 
         if os.path.isdir(path):
             strip_prefix_len = len(path) - len(basename(path))
             for parent, dirs, files in os.walk(path):
                 dest_dir = pjoin(nbext, parent[strip_prefix_len:])
                 if not os.path.exists(dest_dir):
                     if verbose >= 2:
                         print("making directory %s" % dest_dir)
                     os.makedirs(dest_dir)
                 for file in files:
                     src = pjoin(parent, file)
                     # print("%r, %r" % (dest_dir, file))
                     dest = pjoin(dest_dir, file)
                     _maybe_copy(src, dest, verbose)
         else:
             src = path
             _maybe_copy(src, dest, verbose)
 
 #----------------------------------------------------------------------
 # install nbextension app
 #----------------------------------------------------------------------
 
 from IPython.utils.traitlets import Bool, Enum
 from IPython.core.application import BaseIPythonApplication
 
 flags = {
     "overwrite" : ({
         "NBExtensionApp" : {
             "overwrite" : True,
         }}, "Force overwrite of existing files"
     ),
     "debug" : ({
         "NBExtensionApp" : {
             "verbose" : 2,
         }}, "Extra output"
     ),
     "quiet" : ({
         "NBExtensionApp" : {
             "verbose" : 0,
         }}, "Minimal output"
     ),
     "symlink" : ({
         "NBExtensionApp" : {
             "symlink" : True,
         }}, "Create symlinks instead of copying files"
     ),
 }
 flags['s'] = flags['symlink']
 
 aliases = {
     "ipython-dir" : "NBExtensionApp.ipython_dir"
 }
 
 class NBExtensionApp(BaseIPythonApplication):
     """Entry point for installing notebook extensions"""
     
     description = """Install IPython notebook extensions
     
     Usage
     
         ipython install-nbextension file [more files, folders, archives or urls]
     
     This copies files and/or folders into the IPython nbextensions directory.
     If a URL is given, it will be downloaded.
     If an archive is given, it will be extracted into nbextensions.
     If the requested files are already up to date, no action is taken
     unless --overwrite is specified.
     """
     
     examples = """
     ipython install-nbextension /path/to/d3.js /path/to/myextension
     """
     aliases = aliases
     flags = flags
     
     overwrite = Bool(False, config=True, help="Force overwrite of existing files")
     symlink = Bool(False, config=True, help="Create symlinks instead of copying files")
     verbose = Enum((0,1,2), default_value=1, config=True,
         help="Verbosity level"
     )
     
     def install_extensions(self):
         install_nbextension(self.extra_args,
             overwrite=self.overwrite,
             symlink=self.symlink,
             verbose=self.verbose,
             ipython_dir=self.ipython_dir,
         )
     
     def start(self):
         if not self.extra_args:
             nbext = pjoin(self.ipython_dir, u'nbextensions')
             print("Notebook extensions in %s:" % nbext)
             for ext in os.listdir(nbext):
                 print(u"    %s" % ext)
         else:
             self.install_extensions()
 
 
 if __name__ == '__main__':
     NBExtensionApp.launch_instance()
     
  No newline at end of file