BUG: df.groupby(TimeGrouper(freq='48min', closed='right'))
related: #4197, #5694

I'm encoutering a bug in pandas 0.13.0:

``` python
df = pandas.read_hdf('d:\\dropbox\\s.h5', 'data')
df.groupby(TimeGrouper(freq='48min', closed='right'))
```

```
Traceback (most recent call last):
  File "D:/Dropbox/hf/tests/hdf.py", line 94, in <module>
    main()
  File "D:/Dropbox/hf/tests/hdf.py", line 74, in load
    df.groupby(TimeGrouper(freq='48min', closed='right'))
  File "C:\Anaconda\lib\site-packages\pandas\core\generic.py", line 2434, in groupby
    sort=sort, group_keys=group_keys, squeeze=squeeze)
  File "C:\Anaconda\lib\site-packages\pandas\core\groupby.py", line 789, in groupby
    return klass(obj, by, **kwds)
  File "C:\Anaconda\lib\site-packages\pandas\core\groupby.py", line 238, in __init__
    level=level, sort=sort)
  File "C:\Anaconda\lib\site-packages\pandas\core\groupby.py", line 1563, in _get_grouper
    gpr = key.get_grouper(obj)
  File "C:\Anaconda\lib\site-packages\pandas\tseries\resample.py", line 109, in get_grouper
    return self._get_time_grouper(obj)[1]
  File "C:\Anaconda\lib\site-packages\pandas\tseries\resample.py", line 115, in _get_time_grouper
    binner, bins, binlabels = self._get_time_bins(axis)
  File "C:\Anaconda\lib\site-packages\pandas\tseries\resample.py", line 150, in _get_time_bins
    bins = lib.generate_bins_dt64(ax_values, bin_edges, self.closed)
  File "lib.pyx", line 935, in pandas.lib.generate_bins_dt64 (pandas\lib.c:14968)
ValueError: Values falls after last bin
```

This is the max length when it works fine:

``` python
df = pandas.read_hdf('d:\\dropbox\\s.h5', 'data')
df = df[:23748]
df.groupby(TimeGrouper(freq='48min', closed='right'))
```

Also it works when I group it with TimeGrouper(freq='48min')

Here is data frame:
https://www.dropbox.com/s/ezrjralhb2yordm/s.h5

```
INSTALLED VERSIONS
------------------
Python: 2.7.5.final.0
OS: Windows
Release: 8
Processor: Intel64 Family 6 Model 62 Stepping 4, GenuineIntel
byteorder: little
LC_ALL: None
LANG: None

pandas: 0.13.0
Cython: 0.19.2
Numpy: 1.7.1
Scipy: 0.13.2
statsmodels: 0.5.0
    patsy: 0.2.1
scikits.timeseries: Not installed
dateutil: 1.5
pytz: 2013b
bottleneck: Not installed
PyTables: 3.0.0
    numexpr: 2.2.2
matplotlib: 1.3.1
openpyxl: 1.6.2
xlrd: 0.9.2
xlwt: 0.7.5
xlsxwriter: Not installed
sqlalchemy: 0.8.3
lxml: 3.2.3
bs4: 4.3.1
html5lib: Not installed
bigquery: Not installed
apiclient: Not installed
```
