Thanks to Greg Troxel for reporting, and Barry Fishman for the
explanation and fix.
* test-suite/tests/popen.test ("open-input-pipe"): Use shell function
`read' with an explicit argument, as apparently not all shells
support read with no argument.
On the one hand we want the child process in these tests to exit. On
the other, we don't want it to exit before the parent Guile code has
tested the relevant condition (EOF in the first test, broken pipe in
the second) - because these conditions would obviously be true if the
child had already exited, and that's not what we're trying to test
here. We're trying to test getting EOF and broken pipe while the
child process is still alive.
* test-suite/tests/popen.test (open-input-pipe:no duplicate): Add
another pipe from parent to child, so that the child can finish by
reading from this. Then the parent controls the child lifetime by
writing to this pipe.
* test-suite/tests/popen.test (open-output-pipe:no duplicate): Add
another pipe from child to parent, and have the child finish by
endlessly writing into this. Then the parent controls the child
lifetime by closing its end of the pipe, causing a broken pipe in
the child.
