Description of problem:
A named pipe interferes with the use of "grep -sr <term> <directory>" to search
an entire directory tree in a reliable way.

Version-Release number of selected component (if applicable):
grep-2.5.1-52.2

How reproducible:
Always

Steps to Reproduce:
1. mkdir dir1
2. cd dir1; mkfifo fifo
3. cd ..; grep -sr foo . &
4. strace -p <pid-of-grep-above>
  
Actual results:
$ strace -p 3044
Process 3044 attached - interrupt to quit
open("dir1/fifo", O_RDONLY|O_LARGEFILE
## This shows that grep is blocked waiting for the fifo.

Expected results:
Under flags "-sr", grep should not wait for fifos.  Grep should ignore an empty
fifo entirely; and read a non-empty fifo with non-blocking I/O, and assume
End-of-File as soon as the read() returns 0 or -1.  Or, there should be another
command-line flag to specify the behavior "don't wait for fifos", so that there
is some reliable way to search a directory tree for strings.

Additional info: