Ensure virtualenv activates.

There are two changes:
 * remove quoting which causes virtuaenv not activate
 * check virtualenv actually activated

If the quoting added in the fix in #8394 (4ff8d3ad9cea) kicks in, it
causes virtualenv to fail to activate.

For the common case it is no op:
```python
>>> from pipes import quote
>>> print quote('common/case')
common/case
```

When the path actually needs quoting, this is what happens:

```python
>>> print quote('test spaces')
'test spaces'
>>> print quote('windows\\path')
'windows\\path'
```

Note the embedded quotes.

Virtualenv in activate_this.py uses __file__ to build the path that
should be added to PATH:

```python
>>> print os.getcwd()
C:\software\git
>>> print os.path.abspath(quote('windows\\path'))
C:\software\git\'windows\path'
>>>
```

The constructed path is not valid. Adding it at the beginning of PATH
has no effect. This issue affects any case when the call to `quote`
kicks in.

0 files changed, 0 insertions, 0 deletions