Why does my bash script show messages like “foo.sh: line 55: wait_for: No record of process 60227”?

Issue

A bash script that activates the lastpipe behavior sometimes shows error messages like

foo.sh: line 55: wait_for: No record of process 60227

The script has the following characteristics:

• Sets the lastpipe behavior
• Has a “while read from a pipe” loop
• The last command in the loop is a read from a pipe
• At least one external command is executed inside the loop before the read

Example:

#!/bin/bash
shopt -s lastpipe
seq 1000 1010 | while read dummy1
do
  /bin/true
  /bin/true | read dummy2
done