[yt-dev] Issue #1297: ds.print_stats() fails (yt_analysis/yt)

[yurivict]

New issue 1297: ds.print_stats() fails
https://bitbucket.org/yt_analysis/yt/issues/1297/dsprint_stats-fails

yurivict:

The example from http://yt-project.org/doc/quickstart/data_inspection.html fails:
```
import yt
ds = yt.load("IsolatedGalaxy/galaxy0030/galaxy0030")
ds.print_stats()
```

```
$ python2 chapter-inspect.py 
yt : [INFO     ] 2016-11-17 00:12:48,682 Parameters: current_time              = 0.00600002000283
yt : [INFO     ] 2016-11-17 00:12:48,682 Parameters: domain_dimensions         = [32 32 32]
yt : [INFO     ] 2016-11-17 00:12:48,683 Parameters: domain_left_edge          = [ 0.  0.  0.]
yt : [INFO     ] 2016-11-17 00:12:48,683 Parameters: domain_right_edge         = [ 1.  1.  1.]
yt : [INFO     ] 2016-11-17 00:12:48,683 Parameters: cosmological_simulation   = 0.0
Traceback (most recent call last):
  File "chapter-inspect.py", line 6, in <module>
    ds.print_stats()
  File "/usr/local/lib/python2.7/site-packages/yt/utilities/parallel_tools/parallel_analysis_interface.py", line 320, in root_only
    return func(*args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/yt/data_objects/static_output.py", line 457, in print_stats
    self.index.print_stats()
  File "/usr/local/lib/python2.7/site-packages/yt/data_objects/static_output.py", line 419, in index
    self, dataset_type=self.dataset_type)
  File "/usr/local/lib/python2.7/site-packages/yt/frontends/enzo/data_structures.py", line 212, in __init__
    GridIndex.__init__(self, ds, dataset_type)
  File "/usr/local/lib/python2.7/site-packages/yt/geometry/geometry_handler.py", line 50, in __init__
    self._setup_geometry()
  File "/usr/local/lib/python2.7/site-packages/yt/geometry/grid_geometry_handler.py", line 51, in _setup_geometry
    self._parse_index()
  File "/usr/local/lib/python2.7/site-packages/yt/frontends/enzo/data_structures.py", line 272, in _parse_index
    pbar = get_pbar("Parsing Hierarchy ", self.num_grids)
  File "/usr/local/lib/python2.7/site-packages/yt/funcs.py", line 414, in get_pbar
    pbar = TqdmProgressBar(title,maxval)
  File "/usr/local/lib/python2.7/site-packages/yt/funcs.py", line 346, in __init__
    self._pbar = tqdm(leave=True, total=maxval, desc=title)
  File "/usr/local/lib/python2.7/site-packages/yt/extern/tqdm/_tqdm.py", line 297, in __init__
    ncols = _environ_cols_wrapper()(file)
TypeError: 'NoneType' object is not callable
```