When using pdb to debug, the traceback is off by one line.

For example, this simple script:

```
print("line 1")
import pdb;pdb.set_trace()
print("line 2")
print("line 3", broken)
print("line 4")
```

...when run produces the following traceback (after hitting 'n' in pdb, of course):

```
Traceback (most recent call last):
  File "/home/facundo/foo.py", line 3, in <module>
    print("line 2")
NameError: name 'broken' is not defined
```