Problem with successive use of readrec

[Dave Bucklin]

I'm trying to fetch data using successivs calls to readrec. The first
one works, but the second returns nothing in REPLY_REC. I've put
together the following example.
Am I doing something wrong, or is this an issue with readrec? 

```
$uname -a
Linux hostname 4.19.0-11-amd64 #1 SMP Debian 4.19.146-1 (2020-09-17) x86_64 
GNU/Linux

$echo $BASH_VERSION
5.0.3(1)-release
```

```
#!/usr/bin/env bash
readrec_path="/usr/lib/recutils/bash-builtins/readrec.so"

enable -f "$readrec_path" readrec

cat <<EOF >readrectest
%rec: State
%key: Id

Id: 1
State: MN
Capital: St. Paul

Id: 2
State: IA
Capital: Des Moines
EOF

#This outputs "Capital=St. Paul"
unset Capital
readrec < <(recsel -t State -e "Id=1" readrectest)
echo "Capital=${Capital}"

#This outputs "Capital=", expecting "Capital=Des Moines"
unset Capital
readrec < <(recsel -t State -e "Id=2" readrectest)
echo "Capital=${Capital}"
```