Fix doctest due to changes in Info (?)

I'm getting a doctest failure caused by `Info` no longer containing `filenames`, so there are 18 non-empty items instead of 19 we had previously, which causes a doctest failure in `python_tutorial.rst`. @Eric89GXL this change seems to be due to 

https://github.com/mne-tools/mne-python/commit/1a75d690b81d2f12398021a1ebc5fa33bfaa8a16#diff-877c1516babd7396e85b4525b5127203

was no longer merging `filenames` intentional?