This line used to be:
```
fnames = [op.abspath(f) if not op.isabs(f) else f for f in fnames]
```
However, the intended logic (`os.path.abspath`) doesn't really work:
```
>>> from os import path
>>> path.isabs('/home/larsoner/../')
True
>>> path.abspath('/home/larsoner/../')
'/home'
```
I think it should be fine if we don't bother checking to see if it was an absolute path before making it an absolute path. Why was that check there? Having it not convert to an absolute path made a test fail now, since I accessed a file using `../../` in the filename somewhere, and then the check in `save` didn't realize I was going to be overwriting the filename that was open (with `preload=False), which is not good.