Sort broken after unique -> Series
I see #1807 issue reoccurring in my setup:

```
>>> Series(Series([1,3,4]).unique())
0    1
1    3
2    4
dtype: int64

```

And this doesn't return anything:

```
>>> Series(Series([1,3,4]).unique()).sort() 

```
## INSTALLED VERSIONS

commit: None
python: 2.7.5.final.0
python-bits: 64
OS: Linux
OS-release: 3.14.4-200.fc20.x86_64
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8

pandas: 0.16.1-13-gf6c7d89
nose: 1.3.0
Cython: 0.21.1
numpy: 1.8.2
scipy: 0.12.1
statsmodels: None
IPython: 0.13.2
sphinx: None
patsy: None
dateutil: 1.5
pytz: 2012d
bottleneck: None
tables: 3.0.0
numexpr: 2.2.2
matplotlib: 1.3.1
openpyxl: None
xlrd: 0.9.3
xlwt: None
xlsxwriter: 0.7.2
lxml: None
bs4: 4.3.2
html5lib: 0.999
httplib2: None
apiclient: None
sqlalchemy: None
pymysql: None
psycopg2: 2.5.1 (dt dec pq3 ext
