Correct stack depth for variable expansion in !system commands

[takluyver]

Closes issue #1878.

[takluyver]

%magic commands already get the right stack depth, it was only a problem for !system commands. I've added tests for both.

[takluyver]

Test results for commit 9e68e27 merged into master
Platform: linux2

• python2.7: OK
• python3.1: OK (libraries not available: cython matplotlib numpy pymongo qt rpy2 wx wx.aui zmq)
• python3.2: OK (libraries not available: cython pymongo wx wx.aui)

Not available for testing: python2.6

[fperez]

Nice, thanks for doing this! BTW, I think we have similar problems with %run, in case you're in the stack-depth mindset ;)

Merging this one now, good work.

[takluyver]

You're welcome. What's the problem with %run? I'm not sure I've come across that.

[fperez]

In master:

In [3]: run ~/scratch/err
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
/home/fperez/ipython/ipython/IPython/utils/py3compat.pyc in execfile(fname, *where)
    176             else:
    177                 filename = fname
--> 178             __builtin__.execfile(filename, *where)

/home/fperez/scratch/err.py in <module>()
      7 f"""
      8 
----> 9 foo33

NameError: name 'foo33' is not defined

In 0.10.2:

In [1]: run /home/fperez/scratch/err
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)

/home/fperez/scratch/err.py in <module>()
      7 f"""
      8 
----> 9 foo33
     10 
     11 

NameError: name 'foo33' is not defined
WARNING: Failure executing file: </home/fperez/scratch/err.py>

In master, we're showing an extra frame from our own code we shouldn't. I just haven't looked at the stack handling code, I'm sure the fix is just a similar frame offseta adjustment b/c we added the extra py3compat layer.

[takluyver]

Ah, tracebacks. I'll see what I can find.

[fperez]

Awesome, thanks!