[mythtv] backend dying while mythweb is creating previews for recorded programs

[Chris Petersen]

> mythweb is using a connection cache when talking with the backend.  If 
> the 4 second timeout is hit when waiting for a response from the backend 
> the fread() will return with no data.  mythweb doesnt catch this and next 
> command sent to the backend will get the response from the previous one.

Ick, did I leave the 4-second timeout?  It should be at least 20.  I set 
it to 4 while I was testing things, must have forgotten to set it back.

-Chris