Set inherit_errexit after bash version check

inherit_errexit wasn’t available in bash 3. We have a check to show a
nice error message, but that check is after we set inherit_errexit in
setup.sh. So we can just move this to below the BASH_VERSINFO check.

pkgs/stdenv/generic/setup.sh

@@ -2,7 +2,6 @@
 __nixpkgs_setup_set_original=$-
 set -eu
 set -o pipefail
-shopt -s inherit_errexit
 
 if [[ -n "${BASH_VERSINFO-}" && "${BASH_VERSINFO-}" -lt 4 ]]; then
     echo "Detected Bash version that isn't supported by Nixpkgs (${BASH_VERSION})"
@@ -10,6 +9,8 @@ if [[ -n "${BASH_VERSINFO-}" && "${BASH_VERSINFO-}" -lt 4 ]]; then
     exit 1
 fi
 
+shopt -s inherit_errexit
+
 if (( "${NIX_DEBUG:-0}" >= 6 )); then
     set -x
 fi