make_unpipe - unpipe a seplib file (therefore back seakable)
make_unpipe(tag)
tag to unpipe
Make sure that a seplib input dataset is not a pipe. If it isn't a pipe we do nothing. If it is we make a temporary dataset and then copy the data to a new file which is made temporary by unlinking it after it has been created. This ensures that it will disappear when the job ends.
WARNING DO NOT CLOSE THE FILE AFTER make_unpipe()
has been called
sep