in the rare case the select() is interrupted while waiting on child statuses, exit...

in the rare case the select() is interrupted while waiting on child statuses, exit early to prevent read()'s on invalid file handles and allow the calling code to loop back around and try again

git-svn-id: svn://svn.open-ils.org/OpenSRF/trunk@2101 9efc2488-bf62-4759-914b-345cdb29e865