Fix filenbmanager.list_dirs fails for Windows user profile directory

[cgohlke]

Using ipython‑2.0.0‑b1, pyzmq-14.1.0, and tornado‑3.2 on win‑amd64‑py3.4rc3, Windows 8.1, I get FileNotFoundError and PermissionError (below) when starting ipython notebook from within the user profile directory.

On Windows >XP, the users profile directories contain hidden junctions such as NetHood or My Documents for backwards compatibility. Calling os.stat and os.listdir on these junctions may fail with various Exceptions.

The patch fixes these exceptions for me on win‑amd64‑py3.4 (not tested on other platforms).

2014-03-11 22:54:58.751 [NotebookApp] Using existing profile dir: 'C:\\Users\\gohlke\\.ipython\\profile_default'
2014-03-11 22:54:58.751 [NotebookApp] Using MathJax from CDN: http://cdn.mathjax.org/mathjax/latest/MathJax.js
2014-03-11 22:54:58.782 [NotebookApp] Serving notebooks from local directory: C:\Users\gohlke
2014-03-11 22:54:58.782 [NotebookApp] 0 active kernels
2014-03-11 22:54:58.782 [NotebookApp] The IPython Notebook is running at: http://127.0.0.1:8888/
2014-03-11 22:54:58.798 [NotebookApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
2014-03-11 22:54:59.085 [NotebookApp] ERROR | Unhandled error in API request
Traceback (most recent call last):
  File "X:\Python34\lib\site-packages\IPython\html\base\handlers.py", line 286, in wrapper
    result = method(self, *args, **kwargs)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\handlers.py", line 75, in get
    dirs = nbm.list_dirs(path)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\filenbmanager.py", line 192, in list_dirs
    if os.path.isdir(os_path) and not is_hidden(os_path, self.notebook_dir)\
  File "X:\Python34\lib\site-packages\IPython\html\utils.py", line 108, in is_hidden
    st = os.stat(path)
FileNotFoundError: [WinError 2] The system cannot find the file specified: 'C:\\Users\\gohlke\\NetHood'
ERROR:tornado.access:{
  "Connection": "Keep-Alive",
  "Accept-Language": "en-US",
  "X-Requested-With": "XMLHttpRequest",
  "User-Agent": "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko",
  "Accept": "application/json, text/javascript, */*; q=0.01",
  "Dnt": "1",
  "Referer": "http://127.0.0.1:8888/tree",
  "Host": "127.0.0.1:8888",
  "Accept-Encoding": "gzip, deflate"
}
ERROR:tornado.access:500 GET /api/notebooks?_=1394603699023 (127.0.0.1) 11.80ms referer=http://127.0.0.1:8888/tree
2014-03-11 22:54:59.093 [NotebookApp] ERROR | Unhandled error in API request
Traceback (most recent call last):
  File "X:\Python34\lib\site-packages\IPython\html\base\handlers.py", line 286, in wrapper
    result = method(self, *args, **kwargs)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\handlers.py", line 75, in get
    dirs = nbm.list_dirs(path)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\filenbmanager.py", line 192, in list_dirs
    if os.path.isdir(os_path) and not is_hidden(os_path, self.notebook_dir)\
  File "X:\Python34\lib\site-packages\IPython\html\utils.py", line 108, in is_hidden
    st = os.stat(path)
FileNotFoundError: [WinError 2] The system cannot find the file specified: 'C:\\Users\\gohlke\\NetHood'
ERROR:tornado.access:{
  "Connection": "Keep-Alive",
  "Accept-Language": "en-US",
  "X-Requested-With": "XMLHttpRequest",
  "User-Agent": "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko",
  "Accept": "application/json, text/javascript, */*; q=0.01",
  "Dnt": "1",
  "Referer": "http://127.0.0.1:8888/tree",
  "Host": "127.0.0.1:8888",
  "Accept-Encoding": "gzip, deflate"
}
ERROR:tornado.access:500 GET /api/notebooks?_=1394603699024 (127.0.0.1) 0.00ms referer=http://127.0.0.1:8888/tree

2014-03-11 23:46:18.002 [NotebookApp] ERROR | Unhandled error in API request
Traceback (most recent call last):
  File "X:\Python34\lib\site-packages\IPython\html\base\handlers.py", line 286, in wrapper
    result = method(self, *args, **kwargs)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\handlers.py", line 75, in get
    dirs = nbm.list_dirs(path)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\filenbmanager.py", line 188, in list_dirs
    dir_names = os.listdir(os_path)
PermissionError: [WinError 5] Access is denied: 'C:\\Users\\gohlke\\My Documents'
ERROR:tornado.access:{
  "Connection": "Keep-Alive",
  "X-Requested-With": "XMLHttpRequest",
  "Referer": "http://127.0.0.1:8889/tree/My%20Documents",
  "Accept-Language": "en-US",
  "Dnt": "1",
  "User-Agent": "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko",
  "Accept-Encoding": "gzip, deflate",
  "Host": "127.0.0.1:8889",
  "Accept": "application/json, text/javascript, */*; q=0.01"
}
ERROR:tornado.access:500 GET /api/notebooks/My%20Documents?_=1394606777923 (127.0.0.1) 4.00ms referer=http://127.0.0.1:8
889/tree/My%20Documents
2014-03-11 23:46:18.037 [NotebookApp] ERROR | Unhandled error in API request
Traceback (most recent call last):
  File "X:\Python34\lib\site-packages\IPython\html\base\handlers.py", line 286, in wrapper
    result = method(self, *args, **kwargs)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\handlers.py", line 75, in get
    dirs = nbm.list_dirs(path)
  File "X:\Python34\lib\site-packages\IPython\html\services\notebooks\filenbmanager.py", line 188, in list_dirs
    dir_names = os.listdir(os_path)
PermissionError: [WinError 5] Access is denied: 'C:\\Users\\gohlke\\My Documents'
ERROR:tornado.access:{
  "Connection": "Keep-Alive",
  "X-Requested-With": "XMLHttpRequest",
  "Referer": "http://127.0.0.1:8889/tree/My%20Documents",
  "Accept-Language": "en-US",
  "Dnt": "1",
  "User-Agent": "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko",
  "Accept-Encoding": "gzip, deflate",
  "Host": "127.0.0.1:8889",
  "Accept": "application/json, text/javascript, */*; q=0.01"
}
ERROR:tornado.access:500 GET /api/notebooks/My%20Documents?_=1394606777926 (127.0.0.1) 0.00ms referer=http://127.0.0.1:8
889/tree/My%20Documents

[minrk]

Can you catch OSError instead of Exception?

[jdfreder]

Also, it looks like this is causing a real failure in the regression tests:

  File "/home/travis/virtualenv/python3.3/lib/python3.3/site-packages/IPython/html/tests/test_files.py", line 42, in test_hidden_files
    r.raise_for_status()

[minrk]

Should be finished up in #5390