[mythtv] GeneratePreviewPixmaps causing frontend to hang

[Chris Petersen]

> I have the same problem here. Workaround is to look at all recordings in
> mythweb (which seems to use some other approach to generating the
> preview images). After doing so, the previews appear just fine in frontend.

Didn't seem to help me.

Either way, it's a bug that needs to be fixed, so I figured I'd report it.

-Chris