a way, but made more serious with the recent changes).
The n>&n operation (more or less a no-op, except it clears CLOEXEC)
should precede almost everything else - and simply be made to fail if
an attempt is made to apply it to a sh internal fd.
We were renumbering the internal fd (the n> part considered first)
which was dumb, but OK, before, but now rejecting the operation
(the >&n) part when n should not be visible to the script. That
made something of a mess (and could lead to the shell believing its
job control tty was at a fd it never got moved to).
Do things in the correct order, and simply fail that case for internal
fds (for every other n>xxx for any xxx sh simply renumbers its internal fd
n to some other fd before attempting the operation, even n>&- ... those are
all fine).
[In all the above the '>' is used in place of any redirect operator].
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