matplotlib/matplotlib — pull request #2597 by tacaswell (2013-11-16 19:55:25+00:00)
Title: BUG: Add subplot spec  eq  

See: http://stackoverflow.com/questions/20017314/how-are-existing-subplot-axes-retrieved-using-subplot2grid-gridspec-in-matplotli

in short,

```
gs = gridspec.GridSpec(2,1)
In [220]: gs[0, 0] == gs[0, 0]
Out[220]: False
```

which breaks the logic of calling `ax = fig.add_subplot(gs[0,0])` multiple times.