I don't think the terminal even uses this clear_output (it uses the one in core/displaypub) and when I was testing clear_output in qtconsole, I was unsure of what I was supposed to be looking for.  In master, clear_output doesn't seem to do anything to the stream output inside the qtconsole.

I tried something along the lines of:
```python
from time import sleep
from IPython.display import clear_output
for i in range(10):
    clear_output(False)
    print str(i),
    sleep(0.5)
```
which didn't work.  But this does work:

```python
from time import sleep
for i in range(10):
    print '\r' + str(i),
    sleep(0.5)
```