add tests for other == -1/2 with e == -1 [skip ci]

Since the code is already tested, I ran the tests locally for
the coverage tests that were added:

>>> e = 1/(1 - sqrt(2))
>>> assert sqrt(e) == I/sqrt(-1 + sqrt(2))
>>> assert e**-S.Half == -I*sqrt(-1 + sqrt(2))
>>>

C:\Users\sympy>\s\q

C:\Users\sympy>\s\test quality

C:\Users\sympy>\Python27\python.exe bin\test  quality
============================= test process starts =============================
executable:         C:\Python27\python.exe  (2.7.7-final-0) [CPython]
architecture:       32-bit
cache:              yes
ground types:       python
random seed:        70080601
hash randomization: on (PYTHONHASHSEED=3534719981)

sympy\utilities\tests\test_code_quality.py[5] .....                        [OK]

================= tests finished: 5 passed, in 24.62 seconds ==================