Avoid the name `hprNNNN.png` when creating/posting shows
The Internet Archive generates a file called
<identifier>.png for every item created. This is a waveform generated from the main audio file. For HPR shows the identifier is of the form
hpr1234 for show number 1234, so in this case the auto-generated image file will be called
We should avoid this name when adding PNG pictures to episodes. If such a file is uploaded it will replace the auto-generated file, and since this is displayed on the IA website, doing this will mess up the way in which the show is displayed.
What is worse is that there seems to be no way of re-running the auto-generation of the file, so it will presumably be lost forever.