Why doesn't sh with errexit work with a command list?

Question

If I run the following shell script as a normal user, it aborts at line three as expected:

set -o errexit

echo foo > /bar
echo $?

Here is the output:

$ sh test1.sh 
test.sh: 3: test.sh: cannot create /bar: Permission denied

However, if the echo command is a part of a compound list, the execution continues after the failing command and prints the exit code:

set -o errexit

{ echo foo; } > /bar
echo $?

Here is the output:

$ sh test2.sh 
test.sh: 3: test.sh: cannot create /bar: Permission denied
2

How come the script doesn't abort? On the other hand, if I change the curly braces to parentheses it works like how I would expect.

Answer 1

The POSIX specification states that a shell "may exit" if a redirection error occurs with a compound command.

bash chooses to exit if the compound command is a subshell command ((...)), but otherwise chooses not to. I am not aware of the rationale for this distinction; it may be historical in nature.

set -e has many quirks, and often will not behave the way you expect. Many people advise that you simply not use it.