Backport PR
#2717: One liner to fix debugger printing stack traces when lines of context are larger than source....
Backport PR
#2717: One liner to fix debugger printing stack traces when lines of context are larger than source.
Correctly print stack traces when context is larger than lines of source.
To test:
```
In [6]: def bar():
...: return 20
...:
```
Before:
```
In [7]: ipdb.runcall(bar)
<ipython-input-6-d0ed3bd5e16c>(2)bar()
0 return 20
```
And here's after:
```
In [6]: ipdb.runcall(bar)
<ipython-input-5-d0ed3bd5e16c>(2)bar()
1 def bar():
----> 2 return 20
```
Replaces gh-2697. (Adds a test.)
