fetchart: Check that image files are in fact files

[kelvinhammond]

I have no idea why it was a directory, I fixed it manually but still beets should probably check that what it is trying to copy to a file is actually a file and not some other type of "file".

Error: Is a directory while copying /Cashmere Cat - Mirror Maru (Remixes) - 2013/Folder.jpg to/Cashmere Cat - Mirror Maru (
Remixes) - 2013/cover.jpg

<music root>/Cashmere Cat - Mirror Maru (Remixes) - 2013/Folder.jpg was a directory with a file inside of it for the cover, not sure why it was like that but I fixed it.

This may be an issue with the cover art plugin, am not sure, it probably is.

[sampsyo]

Thanks for the thorough report. The fetchart plugin should indeed verify that the stuff it finds are in fact files (i.e., with os.path.isfile).