A FIFO apparently hangs sxiv

[ropery]

First, create a FIFO, and write an image to it,

mkfifo p
convert -size 100x100 xc:black png:- > p

In another terminal, do

sxiv p

sxiv opens the FIFO, but does not read it.

What's more confusing, when you open multiple files including a FIFO, e.g.

sxiv a.png p

The sxiv window is opened, a.png displayed, you hit n, the cursor turns to "loading" & sxiv hangs forever.
I got confused trying to open a directory with sxiv /my/directory/, which happened to contain a FIFO. I thought it was a giant GIF!

Worse, there is no way to exit sxiv from the GUI; sxiv does not respond to q or window-close. You have to kill the process. I'll open this as a separate issue, #253.

To sum it up:
Should sxiv detect a FIFO and reject to load the file, since it cannot do anything with it anyway?