What the test is doing is creating a bunch of pipes,
writing the string MSG to them, and then reading them back.  test_poll1() has just picked a random pipe that's ready for reading, and tried to read MSG_LEN bytes, but instead it 
got back the empty string.  Print the contents of the 
'ready' list and of the 'ready_readers' list constructed from it; maybe find_ready_readers in the test module is buggy.  (Or maybe this behaviour is legal for some reason, 
and the assertion is too stringent.)

I could get a log in on the FreeBSD machine at SourceForge
and look into this.

The test_poll1() function was contributed by Jeremy, BTW,
so if he has access to your FreeBSD machine, he could
also look into it.