Allow drop bins when using the cut function
- [ ] if cut(x, bins=[0, 1, 2, 3, 4, 5, 6, 6, 8, 8, 10], labels=False, retbins=True, right=False) will raise ValueError: You can drop duplicate edges by setting the 'duplicates' kwarg, so add 'duplicates' parameters to the cut function.

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20947?src=pr&el=h1) Report
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> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/20947/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/20947?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #20947   +/-   ##
=========================================
  Coverage          ?   91.82%           
=========================================
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  Branches          ?        0           
=========================================
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| Flag | Coverage Δ | |
|---|---|---|
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| #single | `41.85% <ø> (?)` | |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/20947?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/reshape/tile.py](https://codecov.io/gh/pandas-dev/pandas/pull/20947/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS90aWxlLnB5) | `93.37% <ø> (ø)` | |

------

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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20947?src=pr&el=footer). Last update [8e2a4a9...46c9bca](https://codecov.io/gh/pandas-dev/pandas/pull/20947?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Hello @FANGOD! Thanks for updating the PR.





Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on May 10, 2018 at 18:27 Hours UTC ``duplicates=drop`` drop non-uniques

    >>> pd.cut(s, [0, 2, 4, 6, 10, 10], labels=False, retbins=True,
    ...    right=False, duplicates='drop')
    ... # doctest: +ELLIPSIS
    (a    0.0
     b    1.0
     c    2.0
     d    3.0
     e    3.0
     dtype: float64, array([0, 2, 4, 6, 8]))
 I don't know what to do. Your ci is too 666. ok linted and added a test. ping on green. thanks @FANGOD  Finally. Good experience. 