read -a causes arrays to be malformed

[Thorsten Glaser]

This was indirectly spotted by izabera:

{ IFS= read -arN1 tape[i]; let i++; IFS= read -arN1 tape[i]; } <<<xy; typeset -p tape

This outputs:

set -A tape
typeset -i tape[0]=120
typeset -i tape[0]=121

Obviously, we cannot have duplicate indicēs.

The trigger is trying to read into an array index, which we cannot do as we do not have nested arrays yet.

[Thorsten Glaser (mirabilos)]

Committed revision 100569825E73343E900.