refactor: set pipefail conditionally

src/script.sh

@@ -1,9 +1,7 @@
 #!/bin/sh
 
-# dash does not support pipefail
-# this does not work in `dash script.sh`
-IS_DASH=$(readlink -f "/bin/sh" | grep "dash" || [ $? = 1 ])
-if [ -n "$IS_DASH" ]; then
+if ! (set -o pipefail 2>/dev/null); then
+  # dash does not support pipefail
   set -efx
 else
   set -efx -o pipefail
@@ -14,7 +12,6 @@ if [ -n "$BASH_VERSION" ]; then
   shopt -s expand_aliases
 fi
 
-
 ## Use GNU grep, busybox grep is not as performant
 DISTRO=""
 if [ -f "/etc/os-release" ]; then