reads of pty master will hang indefinitely while slave is closed
If you close the slave side of a pty and read the master you get a single 0-byte read to let you know he slave has closed. If you then for any reason read again, you will hang indefinitely.
I think what happens is that we sleep in the read, and hope the slave gets re-opened and written to. If it does, we'll awaken and return the data from the read.
I suspect there are compatibility implications to doing what everyone else does and failing any read while the slave is closed.
I'm filing this as a means to record the details, it likely is not something we should ever fix.