Error when plotting with datetime indexes on a one month range
#### Code Sample, a copy-pastable example if possible

```python
import pandas as  pd
from matplotlib import pyplot as plt

l = []
for d in pd.date_range(pd.datetime(2017, 1, 1), pd.datetime(2017, 12, 31)):
    l.append([d, 1])
    
data = pd.DataFrame(columns=['Date', 'Values'], data=l)
data.index = data['Date']

plt.figure()
data['Values'].plot()  # should work
plt.show()

plt.figure()
data.loc[pd.datetime(2017, 1, 1):pd.datetime(2017, 1, 31)]['Values'].plot()  # does not work for me
plt.show()

```
#### Problem description
The index of the dataframe are datetimes (everything works fine if they are just integers). When I plot the whole data, there is no error, but if I want to plot a single month, like in the second part of the code, then I get the error:

```
Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/matplotlib/texmanager.py", line 486, in make_png
    stderr=subprocess.STDOUT)
  File "/usr/lib/python3.6/subprocess.py", line 336, in check_output
    **kwargs).stdout
  File "/usr/lib/python3.6/subprocess.py", line 418, in run
    output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['dvipng', '-bg', 'Transparent', '-D', '100.0', '-T', 'tight', '-o', 'f5e9ce5af00a173bfe282bcbe3d5ed2e.png', '6be67e2d9c3c0e0576f96f57d2840f89.dvi']' returned non-zero exit status 1.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.6/tkinter/__init__.py", line 1699, in __call__
    return self.func(*args)
  File "/usr/lib/python3.6/tkinter/__init__.py", line 745, in callit
    func(*args)
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_tkagg.py", line 323, in idle_draw
    self.draw()
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_tkagg.py", line 304, in draw
    FigureCanvasAgg.draw(self)
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_agg.py", line 430, in draw
    self.figure.draw(self.renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/figure.py", line 1295, in draw
    renderer, self, artists, self.suppressComposite)
  File "/usr/lib/python3.6/site-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 2399, in draw
    mimage._draw_list_compositing_images(renderer, self, artists)
  File "/usr/lib/python3.6/site-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/axis.py", line 1138, in draw
    tick.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/axis.py", line 282, in draw
    self.label1.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/text.py", line 799, in draw
    mtext=mtext)
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_agg.py", line 250, in draw_tex
    Z = texmanager.get_grey(s, size, self.dpi)
  File "/usr/lib/python3.6/site-packages/matplotlib/texmanager.py", line 545, in get_grey
    pngfile = self.make_png(tex, fontsize, dpi)
  File "/usr/lib/python3.6/site-packages/matplotlib/texmanager.py", line 493, in make_png
    exc.output.decode("utf-8"))))
RuntimeError: dvipng was not able to process the following string:
b''

Here is the full report generated by dvipng:
6be67e2d9c3c0e0576f96f57d2840f89.dvi: No such file or directory
This is dvipng (dvipng (TeX Live)) 1.15 Copyright 2002-2015 Jan-Ake Larsson
 


Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/matplotlib/texmanager.py", line 486, in make_png
    stderr=subprocess.STDOUT)
  File "/usr/lib/python3.6/subprocess.py", line 336, in check_output
    **kwargs).stdout
  File "/usr/lib/python3.6/subprocess.py", line 418, in run
    output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['dvipng', '-bg', 'Transparent', '-D', '100.0', '-T', 'tight', '-o', 'f5e9ce5af00a173bfe282bcbe3d5ed2e.png', '6be67e2d9c3c0e0576f96f57d2840f89.dvi']' returned non-zero exit status 1.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.6/tkinter/__init__.py", line 1699, in __call__
    return self.func(*args)
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_tkagg.py", line 233, in resize
    self.show()
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_tkagg.py", line 304, in draw
    FigureCanvasAgg.draw(self)
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_agg.py", line 430, in draw
    self.figure.draw(self.renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/figure.py", line 1295, in draw
    renderer, self, artists, self.suppressComposite)
  File "/usr/lib/python3.6/site-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/axes/_base.py", line 2399, in draw
    mimage._draw_list_compositing_images(renderer, self, artists)
  File "/usr/lib/python3.6/site-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
    a.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/axis.py", line 1138, in draw
    tick.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/axis.py", line 282, in draw
    self.label1.draw(renderer)
  File "/usr/lib/python3.6/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
    return draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3.6/site-packages/matplotlib/text.py", line 799, in draw
    mtext=mtext)
  File "/usr/lib/python3.6/site-packages/matplotlib/backends/backend_agg.py", line 250, in draw_tex
    Z = texmanager.get_grey(s, size, self.dpi)
  File "/usr/lib/python3.6/site-packages/matplotlib/texmanager.py", line 545, in get_grey
    pngfile = self.make_png(tex, fontsize, dpi)
  File "/usr/lib/python3.6/site-packages/matplotlib/texmanager.py", line 493, in make_png
    exc.output.decode("utf-8"))))
RuntimeError: dvipng was not able to process the following string:
b''

Here is the full report generated by dvipng:
6be67e2d9c3c0e0576f96f57d2840f89.dvi: No such file or directory
This is dvipng (dvipng (TeX Live)) 1.15 Copyright 2002-2015 Jan-Ake Larsson
```

I was using the TkAgg backend, but I had the same issue with the other backends as well.


#### Output of ``pd.show_versions()``

<details>

INSTALLED VERSIONS
------------------
commit: None
python: 3.6.2.final.0
python-bits: 64
OS: Linux
OS-release: 4.13.7-1-ARCH
machine: x86_64
processor: 
byteorder: little
LC_ALL: None
LANG: fr_FR.utf8
LOCALE: fr_FR.UTF-8

pandas: 0.20.3
pytest: 3.2.3
pip: 9.0.1
setuptools: 36.6.0
Cython: 0.27.1
numpy: 1.13.3
scipy: 0.19.1
xarray: None
IPython: 6.2.1
sphinx: 1.6.4
patsy: None
dateutil: 2.6.1
pytz: 2017.2
blosc: None
bottleneck: 1.2.1
tables: None
numexpr: 2.6.4
feather: None
matplotlib: 2.1.0
openpyxl: None
xlrd: 1.1.0
xlwt: 1.3.0
xlsxwriter: None
lxml: None
bs4: 4.6.0
html5lib: 0.999999999
sqlalchemy: 1.1.14
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
pandas_gbq: None
pandas_datareader: 0.5.0

</details>
