to_clipboard has no effect in ipython (works in python) (linux)
#### Code Sample, a copy-pastable example if possible

```python
# Your code here
import pandas as pd
a=pd.DataFrame([0,1,23])
a.to_clipboard()

```
#### Problem description
Hi
since several months I am no longer able to use the to_clipboard function in ipython - nothing pasted to clipboard.  I notice it works in python!!.  I have tried using latest version of ipython/pandas on anaconda but no improvement

#### Expected Output
I expect to paste dataframe into text file etc.
#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.6.3.final.0
python-bits: 64
OS: Linux
OS-release: 4.15.0-34-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_GB.UTF-8
LOCALE: en_GB.UTF-8

pandas: 0.23.4
pytest: 3.7.2
pip: 9.0.3
setuptools: 40.2.0
Cython: 0.26.1
numpy: 1.13.3
scipy: 1.0.0
pyarrow: 0.7.1
xarray: None
IPython: 6.5.0
sphinx: 1.6.3
patsy: 0.4.1
dateutil: 2.7.3
pytz: 2014.10
blosc: None
bottleneck: 1.2.1
tables: 3.4.2
numexpr: 2.6.2
feather: None
matplotlib: 2.1.0
openpyxl: 2.4.8
xlrd: 1.1.0
xlwt: 1.3.0
xlsxwriter: 1.0.2
lxml: 4.1.0
bs4: 4.4.1
html5lib: 0.9999999
sqlalchemy: 1.0.14
pymysql: None
psycopg2: 2.7.1 (dt dec pq3 ext lo64)
jinja2: 2.7.3
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None


</details>
