Series.reset_index not working with "inplace=True"
When I call reset_index on a Series object with arguments inplace=True, it does not work. See the code example below. Am I missing something here? (I am using "0.9.0", checked with pandas.**version**)

``` python
ts_a = pandas.Series([1]*3+[2]*3+[3]*4, range(10))
ts_b = pandas.Series([2]*3+[3]*3+[1]*4, range(10))
ts_c = pandas.Series(numpy.random.randn(10), range(10))
df = pandas.DataFrame({"A": ts_a, "B": ts_b, "C":ts_c})
df = df.set_index(['A', 'B'])['C'] # I select column C here to have a Series object
# print df
# A  B
#1  2    1.032
#    2    0.139
#    2   -0.708
#2  3   -1.268
#    3    0.138
#    3    0.497
#3  1    0.973
#    1   -0.634
#    1   -0.112
#    1   -0.997

# now let's reset index 'B': inplace does not work?
df.reset_index('B', inplace=True)
# print df
# A  B
#1  2    1.032
#    2    0.139
#    2   -0.708
#2  3   -1.268
#    3    0.138
#    3    0.497
#3  1    0.973
#    1   -0.634
#    1   -0.112
#    1   -0.997

# when copied, it does work
df = df.reset_index('B')
# print df
# Name: C
#    B      C
# A          
#1  2  1.032
#1  2  0.139
#1  2 -0.708
#2  3 -1.268
#2  3  0.138
#2  3  0.497
#3  1  0.973
#3  1 -0.634
#3  1 -0.112
#3  1 -0.997
```
