Robots.txt path incorrect when Disallow is empty

Hi,
If `robots.txt` contains Disallow line with no path, joomscan incorrectly displays the interesting path.
robots.txt:
```
User-agent: *
Disallow:
```
Output:
```
[++] robots.txt is found
path : http://target.example.org/robots.txt 

Interesting path found from robots.txt
http://target.example.orgisallow:
```
